Avoid mutt sending mail with too many entries in To: or Cc: fields

emailmutt

Frequently, I use mutt's alias functionality, to send a message to larger groups of people (legitimate, not spam!). Normally, I put the alias into the Bcc: field, to cancel out spam harvesters, and for privacy reasons (not all recipient know each other).

By accident, I sometimes put the alias into the To: or Cc: field, where it is expanded, revealing all addresses do all recipients. This is very bad, since once sent, the information is leaked, and there's no way back.

How can I make mutt refuse to send a mail, if there is more than, say, 1 entry in the To: or 5 entries in the Cc: field?
Improvement: How can I make mutt send the mail anyways, if I add a user-defined header, e.g., X-limit-cc: 50?

Setting up a separate mailing list service is not what I'm asking for, this would rather be a separate solution to the problem.

Best Answer

AFAIK, Mutt itself cannot do such checks, but there's a workaround! The idea is to redefine the $sendmail variable to use a wrapper that will check the mail before sending it. For instance, in your .muttrc file:

set sendmail=$HOME/scripts/sendmail-mutt

This script can either terminate with an error (non-zero exit status) or terminate successfully with something like:

exec /usr/sbin/sendmail -oem -oi "$@"

in a shell script, or:

exec qw(/usr/sbin/sendmail -oem -oi), @ARGV;

in Perl.

Related Solutions

Bash – Script to email all matching files in a directory

set "/home/user/path to files/"*.xls
for f do [ "$f" -nt "$two_day_old_file" ] && set "$@" "$f" ; shift ; done
touch "$two_day_old_file"
echo $MBODY | mutt -s "Data files for $TODAY" -a "$@" -- $EMAILS

To mail them one at a time change the echo line to:

for mailf do echo "$MBODY" | 
    mutt -s "Data files for $TODAY" -a "$mailf" -- $EMAILS
done

Would probably work, but your real problem lies here:

...
set IFS=...
...

This doesn't affect the value of the internal field separator at all, but rather it assigns the value IFS=... to the first positional parameter, or $1. $IFS remains valued at whatever it was before you set $1. You just need to do:

IFS='
   '

Or...

IFS=${IFS# }

...if $IFS is set to the default value, which it must be if this is an executable script and you have not altered $IFS anywhere else in the script.

Automatically send from specific email addresses in Mutt

You can configure mutt to use different from addresses (via your ~/.muttrc), e.g.:

set use_from = yes
set envelope_from = yes
set from = default@example.org
set realname = "Default Realname"
# list of all your addresses
alternates @example\.org$

You can setup some macros to explicitly switch the from before composing a new mail:

macro index \e1 "set from=foo@example.org\n" "Select foo address"
macro index \e2 "set from=bar@example.org\n" "Select bar address"
# ...

When replying to an email, you can configure mutt to automatically use the to-header as from address (this is point 2 from your question):

set reverse_name=yes

Don't reuse the real name - helps when people send you crap like "foo@example.org" <foo@example.org>:

set reverse_realname=no

Then you can set up some hooks to make things depend on header values - e.g. to use different fcc folders:

fcc-hook '~f ^foo@example\.org' '=foo'

(There are also other hooks, like send-hook etc.)

I would look into the hooks to implement something like point 1 from your question. Although, you would need some external scripting to maintain such a database.

Depending on your current MTA setup you may have to change its config as well, i.e. such that it accepts different envelope froms.

It is also possible to use different SMTP relays depending on e.g. the hostname of the envelope from - but this must be configured in the MTA.

Best Answer

Related Solutions

Bash – Script to email all matching files in a directory

Automatically send from specific email addresses in Mutt

Related Question