mail(1) cannot send to address containing an equals sign

[Ralph Corderoy]

Binary package hint: mailutils

Ubuntu 8.04, mailutils 1:1.1+dfsg1-3.1.

Attempting to unsubscribe from a mailing list, I did

    mail announce-unsubscribe-subversion=$<email address hidden> </dev/null

(`$private' is me replacing a simple plain domain name I wish to keep
private.)

mail(1) returned without error. Later, I receive various bounces. mail
gave the Postfix SMTP server on localhost three separate recipient
addresses.

    <email address hidden>
    <=@inputplus.co.uk>
    <$<email address hidden>>

Postfix has added the `@inputplus.co.uk' to those addresses it was given
that didn't have domain names. So mail(1) handed over

    announce-unsubscribe-subversion
    =
    $<email address hidden>

IOW, it seems to consider the equals sign as a word boundary and split
the desired address there, resulting in three addresses, one just `='.
I suspect this is because during argument processing, mail(1) seems to
turn the contents of files like ~/.mailrc into command line arguments
that precede those given by the user, and the processing of these
handles things like `foo=bar' to set a variable. This probably splits
it into `foo', `=', `bar', and it is later treated as three destination
email addresses.

Note, other destinations like

    mail foo,bar </dev/null

result in email being sent to `foo' and `bar'. I don't know if this is
deliberate, but it doesn't appear to be documented in
http://www.gnu.org/software/mailutils/manual/mailutils.html.gz#mail

Regardless, mail(1) cannot send to the valid unsubscribe address
mandated by a mailing list and is erroneously splitting the address into
parts.

[Nathan Baum (nbaum)]

This is still present in 9.04, with mailutils 1:1.2+dsfg1-4

[Nathan Baum (nbaum)]

Using strace, I can see mail opens a pipe to /usr/sbin/sendmail and sends, in the case of an intended recipient of "foo=bar", a To header of

To: <foo@athens>, <=@athens>, <bar@athens>

athens is the name of the local host, so the fault seems to clearly lie with mailutils.