aerc-config(5)
# NAME
aerc-config - configuration file formats for *aerc*(1)
# CONFIGURATION
There are three aerc config files: *aerc.conf*, *binds.conf*, and
*accounts.conf*. The last one must be kept secret, as it may include your
account credentials. We look for these files in your XDG config home plus
"aerc", which defaults to ~/.config/aerc.
Examples of these config files are typically included with your installation of
aerc and are usually installed in /usr/share/aerc.
Each file uses the _ini_ format, and consists of sections with keys and values.
A line beginning with # is considered a comment and ignored, as are empty lines.
New sections begin with [section-name] on a single line, and keys and values are
separated with "=".
# AERC.CONF
This file is used for configuring the general appearance and behavior of aerc.
## GENERAL OPTIONS
These options are configured in the *[general]* section of aerc.conf.
*default-save-path*
Used as a default path for save operations if no other path is specified.
*pgp-provider*
If set to "gpg", aerc will use system gpg binary and keystore for all
crypto operations. Otherwise, the internal openpgp implementation will
be used.
Default: internal
*unsafe-accounts-conf*
By default, the file permissions of accounts.conf must be restrictive
and only allow reading by the file owner (_0600_). Set this option to
*true* to ignore this permission check. Use this with care as it may
expose your credentials.
Default: false
## UI OPTIONS
These options are configured in the *[ui]* section of aerc.conf.
*index-format*
Describes the format for each row in a mailbox view. This field is
compatible with mutt's printf-like syntax.
Default: %D %-17.17n %s
[- *Format specifier*
:[ *Description*
| %%
: literal %
| %a
: sender address
| %A
: reply-to address, or sender address if none
| %C
: message number
| %d
: formatted message timestamp
| %D
: formatted message timestamp converted to local timezone
| %f
: sender name and address
| %F
: author name, or recipient name if the message is from you.
The address is shown if no name part.
| %g
: message labels (for example notmuch tags)
| %i
: message id
| %n
: sender name, or sender address if none
| %r
: comma-separated list of formatted recipient names and addresses
| %R
: comma-separated list of formatted CC names and addresses
| %s
: subject
| %t
: the (first) address the new email was sent to
| %T
: the account name which received the email
| %u
: sender mailbox name (e.g. "smith" in "smith@example.net")
| %v
: sender first name (e.g. "Alex" in "Alex Smith <smith@example.net>")
| %Z
: flags (O=old, N=new, r=answered, D=deleted, !=flagged, \*=marked)
*timestamp-format*
See time.Time#Format at https://godoc.org/time#Time.Format
Default: "2006-01-02 03:04 PM" (ISO 8601 + 12 hour time)
*this-day-time-format*
Index-only time format for messages that were received/sent today.
If this is not specified, *timestamp-format* is used instead.
Default: ""
*this-week-time-format*
Index-only time format for messages that were received/sent within the
last 7 days. If this is not specified, *timestamp-format* is used
instead.
Default: ""
*this-year-time-format*
Index-only time format for messages that were received/sent this year.
If this is not specified, *timestamp-format* is used instead.
Default: ""
*message-view-timestamp-format*
If set, overrides *timestamp-format* for the message view.
Default: ""
*message-view-this-day-time-format*
If set, overrides *timestamp-format* in the message view for messages
that were received/sent today.
Default: ""
*message-view-this-week-time-format*
If set, overrides *timestamp-format* in the message view for messages
that were recieved/sent within the last 7 days.
Default: ""
*message-view-this-year-time-format*
If set, overrides *timestamp-format* in the message view for messages
that were received/sent this year.
Default: ""
*sidebar-width*
Width of the sidebar, including the border. Set to zero to disable the
sidebar.
Default: 20
*empty-message*
Message to display when viewing an empty folder.
Default: (no messages)
*empty-dirlist*
Message to display when no folders exists or are all filtered.
Default: (no folders)
*mouse-enabled*
Enable mouse events in the ui, e.g. clicking and scrolling with the mousewheel
Default: false
*new-message-bell*
Ring the bell when a new message is received.
Default: true
*pinned-tab-marker*
Marker to show before a pinned tab's name.
Default: `
*spinner*
Animation shown while loading, split by spinner-delimiter (below)
Examples:
- spinner = "\-\_-,\_-\_"
- spinner = '. , .'
- spinner = "\,|,/,-"
Default: "[..] , [..] , [..] , [..] , [..], [..] , [..] , [..] "
*spinner-delimiter*
Spinner delimiter to split string into an animation
Default: ","
*sort*
List of space-separated criteria to sort the messages by, see *sort*
command in *aerc*(1) for reference. Prefixing a criterion with "-r "
reverses that criterion.
Example: "from -r date"
Default: ""
*dirlist-format*
Describes the format string to use for the directory list
Default: %n %>r
[- *Format specifier*
:[ *Description*
| %%
: literal %
| %n
: directory name
| %N
: compacted directory name
| %r
: recent/unseen/total message count
| %>X
: make format specifier 'X' be right justified
*dirlist-delay*
Delay after which the messages are actually listed when entering
a directory. This avoids loading messages when skipping over folders
and makes the UI more responsive. If you do not want that, set it to
0s.
Default: 200ms
*dirlist-tree*
Display the directory list as a foldable tree.
Default: false
*dirlist-collapse*
If dirlist-tree is enabled, set level at which folders are collapsed
by default. Set to 0 to disable.
Default: 0
*next-message-on-delete*
Moves to next message when the current message is deleted
Default: true
*auto-mark-read*
Set the "seen" flag when a message is opened in the message viewer.
Default: true
*completion-popovers*
Shows potential auto-completions for text inputs in popovers.
Default: true
*completion-delay*
How long to wait after the last input before auto-completion is triggered.
Default: 250ms
*completion-min-chars*
The minimum required characters to allow auto-completion to be triggered
after *completion-delay*.
Default: 1
*border-char-vertical*
*border-char-horizontal*
Set stylable characters (via the 'border' element) for vertical and
horizontal borders.
Default: spaces
*stylesets-dirs*
The directories where the stylesets are stored. The config takes
a colon-separated list of dirs. If this is unset or if a styleset cannot
be found, the following paths will be used as a fallback in that order:
```
${XDG_CONFIG_HOME:-~/.config}/aerc/stylesets
${XDG_DATA_HOME:-~/.local/share}/aerc/stylesets
/usr/local/share/aerc/stylesets
/usr/share/aerc/stylesets
```
Default: ""
*styleset-name*
The name of the styleset to be used to style the ui elements. The
stylesets are stored in the 'stylesets' directory in the config
directory.
Default: default
Have a look at *aerc-stylesets*(7) as to how a styleset looks like.
*icon-unencrypted*
The icon to display for unencrypted mails. The status indicator is only
displayed if an icon is set.
Default: ""
*icon-encrypted*
The icon to display for encrypted mails.
Default: [e]
*icon-signed*
The icon to display for signed mails where the signature was
successfully validated.
Default: [s]
*icon-signed-encrypted*
The icon to display for signed and encrypted mails where the signature
was successfully verified. The combined icon is only used if set,
otherwise the signed and encrypted icons are displayed separately.
Default: ""
*icon-unknown*
The icon to display for signed mails which could not be verified due to
the key being unknown.
Default: [s?]
*icon-invalid*
The icon to display for signed mails where verification failed.
Default: [s!]
*fuzzy-complete*
When typing a command or option, the popover will now show not only the
items /starting/ with the string input by the user, but it will also show
instances of items /containing/ the string, starting at any position and
need not be consecutive characters in the command or option.
*reverse-msglist-order*
Reverses the order of the message list. By default, the message list is
ordered with the newest (highest UID) message on top. Reversing the
order will put the oldest (lowest UID) message on top. This can be
useful in cases where the backend does not support sorting.
Default: false
*reverse-thread-order*
Reverse display of the mesage threads. Default order is the the intial
message is on the top with all the replies being displayed below. The
reverse option will put the initial message at the bottom with the
replies on top.
Default: false
*sort-thread-siblings*
Sort the thread siblings according to the sort criteria for the messages. If
sort-thread-siblings is false, the thread siblings will be sorted based on
the message UID. This option is only applicable for client-side threading
with a backend that enables sorting.
Default: false
*threading-enabled*
Enable a threaded view of messages. If this is not supported by the
backend (IMAP server or notmuch), threads will be built by the client.
Default: false
*force-client-threads*
Force threads to be built client-side. Backends that don't support threading
will always build threads client side.
Default: false
## Contextual UI Configuration
The UI configuration can be specialized for accounts, specific mail
directories and message subjects. The specializations are added using
contextual config sections based on the context.
The contextual UI configuration is merged to the base UiConfig in the
following order:
*Base UIConfig > Account Context > Folder Context > Subject Context.*
*[ui:account=<AccountName>]*
Adds account specific configuration with the account name.
*[ui:folder=<FolderName>]*
Add folder specific configuration with the folder name.
*[ui:folder~<Regex>]*
Add folder specific configuration for folders whose names match the regular
expression.
*[ui:subject~<Regex>]*
Add specialized ui configuration for messages that match a given regular
expression.
Example:
```
[ui:account=Work]
sidebar-width=...
[ui:folder=Sent]
index-format=...
[ui:folder~Archive/\d+/.*]
index-format=...
[ui:subject~^\[PATCH]
index-format=...
```
## STATUSLINE
These options are configured in the *[statusline]* section of aerc.conf.
*render-format*
Describes the format string for the statusline format.
For a minimal statusline that only shows the current account and
the connection information, use [%a] %c.
To completely mute the statusline (except for push notifications), use
%m only.
Default: [%a] %S %>%T
[- *Format specifier*
:[ *Description*
| %%
: literal %
| %a
: active account name
| %d
: active directory name
| %c
: connection state
| %p
: current path
| %m
: mute statusline and show only push notifications
| %S
: general status information (e.g. connection state, filter, search)
| %T
: general on/off information (e.g. passthrough, threading, sorting)
| %>
: does not print anything but all format specifier that follow will be right justified.
*separator*
Specifies the separator between grouped statusline elements (e.g. for
the %S and %T specifiers in *render-format*).
Default: " | "
*display-mode*
Defines the mode for displaying the status elements.
Options: text, icon
Default: text
## VIEWER
These options are configured in the *[viewer]* section of aerc.conf.
*pager*
Specifies the pager to use when displaying emails. Note that some filters
may add ANSI escape sequences to add color to rendered emails, so you may
want to use a pager which supports ANSI.
Default: less -R
*alternatives*
If an email offers several versions (multipart), you can configure which
mimetype to prefer. For example, this can be used to prefer plaintext over
HTML emails.
Default: text/plain,text/html
*header-layout*
Defines the default headers to display when viewing a message. To display
multiple headers in the same row, separate them with a pipe, e.g. "From|To".
Rows will be hidden if none of their specified headers are present in the
message.
Authentication information from the Authentication-Results header can be
displayed by adding DKIM, SPF or DMARC. To show more information
than just the authentication result, append a plus sign (+) to the header name
(e.g. DKIM+).
Default: From|To,Cc|Bcc,Date,Subject
*show-headers*
Default setting to determine whether to show full headers or only parsed
ones in message viewer.
Default: false
*always-show-mime*
Whether to always show the mimetype of an email, even when it is just a single part.
Default: false
*parse-http-links*
Parses and extracts http links when viewing a message. Links can then be
accessed with the open-link command.
Default: true
## COMPOSE
These options are configured in the *[compose]* section of aerc.conf.
*editor*
Specifies the command to run the editor with. It will be shown in an
embedded terminal, though it may also launch a graphical window if the
environment supports it. Defaults to *$EDITOR*, or *vi*(1).
*header-layout*
Defines the default headers to display when composing a message. To display
multiple headers in the same row, separate them with a pipe, e.g. "To|From".
Default: To|From,Subject
*address-book-cmd*
Specifies the command to be used to tab-complete email addresses. Any
occurrence of "%s" in the address-book-cmd will be replaced with anything
the user has typed after the last comma.
The command must output the completions to standard output, one completion
per line. Each line must be tab-delimited, with an email address occurring as
the first field. Only the email address field is required. The second field,
if present, will be treated as the contact name. Additional fields are
ignored.
This parameter can also be set per account in accounts.conf.
Example:
khard email --remove-first-line --parsable '%s'
Default: none
*reply-to-self*
If set to false, do not mail yourself when replying (e.g., if replying
to emails previously sent by yourself, address your replies to the
original To: and Cc:).
Default: true
*no-attachment-warning*
Specifies a regular expression against which an email's body should be
tested before sending an email with no attachment. If the regexp
matches, aerc will warn you before sending the message. Leave empty to
disable this feature.
Uses Go's regexp syntax, documented at https://golang.org/s/re2syntax.
The "(?im)" flags are set by default (case-insensitive and multi-line).
Example:
no-attachment-warning=^[^>]\*attach(ed|ment)
Default: none
## FILTERS
Filters allow you to pipe an email body through a shell command to render
certain emails differently, e.g. highlighting them with ANSI escape codes.
They are configured in the *[filters]* section of aerc.conf.
The first filter which matches the email's mimetype will be used, so order
them from most to least specific.
You can also match on non-mimetypes, by prefixing with the header to match
against (non-case-sensitive) and a comma, e.g. subject,text will match a
subject which contains "text". Use header,~regex to match against a regex.
aerc ships with some default filters installed in the share directory (usually
_/usr/share/aerc/filters_). Note that these may have additional dependencies
that aerc does not have alone.
The filter commands are invoked with sh -c [command]. The following folders are
appended to the system $PATH to allow referencing filters from their name only.
```
${XDG_CONFIG_HOME:-~/.config}/aerc/filters
${XDG_DATA_HOME:-~/.local/share}/aerc/filters
$PREFIX/share/aerc/filters
/usr/share/aerc/filters
```
The following variables are defined in the filter command environment:
_AERC_MIME_TYPE_
the part MIME type/subtype
_AERC_FILENAME_
the attachment filename (if any)
Note that said email body is converted into UTF-8 before being passed to
filters.
## OPENERS
Openers allow you to specify the command to use for the *:open* action on a
per-MIME-type basis. They are configured in the *[openers]* section of
aerc.conf.
*{}* is expanded as the temporary filename to be opened. If it is not
encountered in the command, the temporary filename will be appened to the end
of the command. Environment variables are also expanded. Tilde is not expanded.
Example:
```
[openers]
text/html=surf -dfgms
text/plain=gvim {} +125
message/rfc822=thunderbird
```
## TRIGGERS
Triggers specify commands to execute when certain events occur.
They are configured in the *[triggers]* section of aerc.conf.
*new-email*
Executed when a new email arrives in the selected folder.
e.g. new-email=exec notify-send "New email from %n" "%s"
Default: ""
Format specifiers from *index-format* are expanded with respect to the new
message.
## TEMPLATES
Templates are used to populate the body of an email. The compose, reply
and forward commands can be called with the -T flag with the name of the
template name.
aerc ships with some default templates installed in the share directory (usually
_/usr/share/aerc/templates_).
These options are configured in the *[templates]* section of aerc.conf.
*template-dirs*
The directory where the templates are stored. The config takes
a colon-separated list of dirs. If this is unset or if a template cannot
be found, the following paths will be used as a fallback in that order:
```
${XDG_CONFIG_HOME:-~/.config}/aerc/templates
${XDG_DATA_HOME:-~/.local/share}/aerc/templates
/usr/local/share/aerc/templates
/usr/share/aerc/templates
```
Default: ""
*new-message*
The default template to be used for new messages.
Default: "new_message"
*quoted-reply*
The default template to be used for quoted replies.
Default: "quoted_reply"
*forwards*
The default template to be used for forward as body.
Default: "forward_as_body"
# ACCOUNTS.CONF
This file is used for configuring each mail account used for aerc. Each section
is the name of an account you want to configure, and the keys & values in that
section specify details of that account's configuration. In addition to the
options documented here, specific transports for incoming and outgoing emails
may have additional configuration parameters, documented on their respective man
pages.
Note that many of these configuration options are written for you, such as
*source* and *outgoing*, when you run the account configuration wizard
(*:new-account*).
*archive*
Specifies a folder to use as the destination of the *:archive* command.
Default: Archive
*check-mail*
Specifies an interval to check for new mail. Mail will be checked at
startup, and every interval. IMAP accounts will check for mail in all
unselected folders, and the selected folder will continue to receive PUSH
mail notifications. Maildir/Notmuch folders must use *check-mail-cmd* in
conjunction with this option. See *aerc-maildir* and *aerc-notmuch* for
more information.
Setting this option to 0 will disable check-mail
Example: 5m
Default: 0
*copy-to*
Specifies a folder to copy sent mails to, usually "Sent".
Default: none
*default*
Specifies the default folder to open in the message list when aerc
configures this account.
Default: INBOX
*folders*
Specifies the comma separated list of folders to display in the sidebar.
Names prefixed with ~ are interpreted as regular expressions.
Default: all folders
*folders-exclude*
Specifies the comma separated list of folders to exclude from the sidebar.
Names prefixed with ~ are interpreted as regular expressions.
Note that this overrides anything from *folders*.
Default: no folders
*enable-folders-sort*
If true, folders are sorted, first by specified folders (see *folders-sort*),
then alphabetically.
Default: true
*folders-sort*
Specifies a comma separated list of folders to be shown at the top of the
list in the provided order. Remaining folders will be sorted alphabetically.
Default: none
*from*
The default value to use for the From header in new emails. This should be
an RFC 5322-compatible string, such as "Your Name <you@example.org>".
Default: none
*aliases*
All aliases of the current account. These will be used to fill in the From:
field. Make sure that your email server accepts this value, or for example
use *aerc-sendmail*(5) in combination with msmtp and --read-envelope-from.
Default: none
*outgoing*
Specifies the transport for sending outgoing emails on this account. It
should be a connection string, and the specific meaning of each component
varies depending on the protocol in use. See each protocol's man page for
more details:
- *aerc-smtp*(5)
*outgoing-cred-cmd*
Specifies an optional command that is run to get the outgoing account's
password. See each protocol's man page for more details.
Default: none
*outgoing-cred-cmd-cache*
By default, the credentials returned by the command will be cached until
aerc is shut down. If set to false, *outgoing-cred-cmd* will be executed
every time an email is to be sent.
Default: true
*pgp-auto-sign*
If true, all outgoing emails from this account will be signed (if a signing
key is available)
Default: false
*pgp-key-id*
Specify the key id to use when signing a message. Can be either short or
long key id. If unset, aerc will look up the key by email
*pgp-opportunistic-encrypt*
If true, any outgoing email from this account will be encrypted when all
recipients (including "cc" and "bcc" field) have a public key available in
the keyring
Default: false
*postpone*
Specifies the folder to save postponed messages to.
Default: Drafts
*send-as-utc*
Converts the timestamp of the Date header to UTC.
Default: false
*source*
Specifies the source for reading incoming emails on this account. This key
is required for all accounts. It should be a connection string, and the
specific meaning of each component varies depending on the protocol in use.
See each protocol's man page for more details:
- *aerc-imap*(5)
- *aerc-maildir*(5)
- *aerc-notmuch*(5)
Default: none
*source-cred-cmd*
Specifies an optional command that is run to get the source account's
password. See each protocol's man page for more details.
*signature-file*
Specifies the file to read in order to obtain the signature to be added
to emails sent from this account.
*signature-cmd*
Specifies the command to execute in *sh* in order to obtain the
signature to be added to emails sent from this account. If the command
fails then *signature-file* is used instead.
*trusted-authres*
Comma-separated list of trustworthy hostnames from which the
Authentication Results header will be displayed. Entries can be regular
expressions. If you want to trust any host (e.g. for debugging),
use the wildcard \*.
# BINDS.CONF
This file is used for configuring keybindings used in the aerc interactive
client. You may configure different keybindings for different contexts by
writing them into different *[sections]* of the ini file. The available contexts
are:
*[messages]*
keybindings for the message list
*[view]*
keybindings for the message viewer
*[view::passthrough]*
keybindings for the viewer, when in key passthrough mode
(toggled with :toggle-key-passthrough)
*[compose]*
keybindings for the message composer
*[compose::editor]*
keybindings for the composer, when the editor is focused
*[compose::review]*
keybindings for the composer, when reviewing the email before it's sent
*[terminal]*
keybindings for terminal tabs
You may also configure account specific key bindings for each context:
*[context:account=<AccountName>]*
keybindings for this context and account, where <AccountName> matches
the account name you provided in *accounts.conf*.
Folder-specific bindings can be configured for message lists:
*[messages:folder=<FolderName>]*
keybindings under this section will be specific to the folder named
<FolderName>. Keybindings from a *folder* specifier will take precedence
over *account* specifiers
Example:
```
[messages:account=Mailbox]
c = :cf path:mailbox/** and<space>
[compose::editor:account=Mailbox2]
[messages:folder=Drafts]
<Enter> = :recall<Enter>
...
```
You may also configure global keybindings by placing them at the beginning of
the file, before specifying any context-specific sections. For each *key=value*
option specified, the _key_ is the keystrokes pressed (in order) to invoke this
keybinding, and _value_ specifies keystrokes that aerc will simulate when the
keybinding is invoked. Generally this is used to execute commands, for example:
rq = :reply -q<Enter>
Pressing r, then q, will simulate typing in ":reply -q<Enter>", and execute
:reply -q accordingly. It is also possible to invoke keybindings recursively in
a similar fashion. Additionally, the following special options are available in
each binding context:
*$noinherit*
If set to "true", global keybindings will not be effective in this context.
Default: false
*$ex*
This can be set to a keystroke which will bring up the command input in this
context.
Default: ':'
In addition to letters, special keys may be specified in <angle brackets>. The
following special keys are supported:
[[ *Name*
:- *Description*
| space
: " "
| semicolon
: ;
| tab
: Tab
| enter
: Enter
| up
: Up arrow
| c-up
: Ctrl+Up
| a-up
: Alt+Up
| down
: Down arrow
| c-down
: Ctrl+Down
| a-down
: Alt+Down
| right
: Right arrow
| c-right
: Ctrl+Right
| a-right
: Alt+Right
| left
: Left arrow
| c-left
: Ctrl+Left
| a-left
: Alt+Left
| pgup
: Page Up
| c-pgup
: Ctrl+PageUp
| a-pgup
: Alt+PageUp
| pgdn
: Page Down
| c-pgdn
: Ctrl+PageDn
| a-pgdn
: Alt+PageDn
| home
: Home
| end
: End
| insert
: Insert
| delete
: Delete
| exit
: Exit
| cancel
: Cancel
| print
: Print screen
| pause
: Pause
| backtab
: Shift+Tab
| c-space
: Ctrl+Space
| a-space
: Alt+Space
| c-a
: Ctrl+a
| a-a
: Alt+a
| c-b
: Ctrl+b
| a-b
: Alt+b
| c-c
: Ctrl+c
| a-c
: Alt+c
| c-d
: Ctrl+d
| a-d
: Alt+d
| c-e
: Ctrl+e
| a-e
: Alt+e
| c-f
: Ctrl+f
| a-f
: Alt+f
| c-g
: Ctrl+g
| a-g
: Alt+g
| c-h
: Ctrl+h
| a-h
: Alt+h
| c-i
: Ctrl+i
| a-i
: Alt+i
| c-j
: Ctrl+j
| a-j
: Alt+j
| c-k
: Ctrl+k
| a-k
: Alt+k
| c-l
: Ctrl+l
| a-l
: Alt+l
| c-m
: Ctrl+m
| a-m
: Alt+m
| c-n
: Ctrl+n
| a-n
: Alt+n
| c-o
: Ctrl+o
| a-o
: Alt+o
| c-p
: Ctrl+p
| a-p
: Alt+p
| c-q
: Ctrl+q
| a-q
: Alt+q
| c-r
: Ctrl+r
| a-r
: Alt+r
| c-s
: Ctrl+s
| a-s
: Alt+s
| c-t
: Ctrl+t
| a-t
: Alt+t
| c-u
: Ctrl+u
| a-u
: Alt+u
| c-v
: Ctrl+v
| a-v
: Alt+v
| c-w
: Ctrl+w
| a-w
: Alt+w
| c-x
: Ctrl+x
| a-x
: Alt+x
| c-y
: Ctrl+y
| a-y
: Alt+y
| c-z
: Ctrl+z
| a-z
: Alt+z
| c-]
: Ctrl+]
| a-]
: Alt+]
| c-[
: Ctrl+[
| a-[
: Alt+[
| c-^
: Ctrl+^
| a-^
: Alt+^
| c-\_
: Ctrl+\_
| a-\_
: Alt+\_
# SEE ALSO
*aerc*(1) *aerc-imap*(5) *aerc-smtp*(5) *aerc-maildir*(5) *aerc-sendmail*(5)
*aerc-notmuch*(5) *aerc-stylesets*(7)
# AUTHORS
Originally created by Drew DeVault <sir@cmpwn.com> and maintained by Robin
Jarry <robin@jarry.cc> who is assisted by other open source contributors. For
more information about aerc development, see https://sr.ht/~rjarry/aerc/.
