sendmail invocation for "empty sender" bounces

[Sebastian Maus]

Hello,

bounce generation with the "empty sender" address is done like this in
several places in the source code:

[...]
     smbuf[0] = "sendmail";
     smbuf[1] = "-i";            /* ignore dots */
     smbuf[2] = "-f";
     smbuf[3] = "<>";
[...]

Unfortunately, "<>" is not recognised as the "empty sender" by our
sendmail implementation. Instead, it expects "" (which looks a lot more
logical to me, too, given that < and > may not be part of an email
address which is what is expected to come after the -f). At the moment,
I use a wrapper to replace "<>" by "" and it works well here.

As the problem is with an interface to other software, I would like to
find out whether it is worthwile to change the bounce address in Cyrus
to a "true" empty sender. This would of course require tests with other
implementations of the sendmail interface, like this:

	/path/to/sendmail -f "" -- testaddress at domain.tld

While my own tests with Postfix, Debian SMail and qmail were all
positive, Sendmail 8.11.3 invented some envelope sender address and
thus failed the test. With Sendmail, "<>" must be used to force the
empty sender. I do not have any newer Sendmail at hand to test.

>From this small set of tested environments, I guess that -- for the
sake of compatibility with Sendmail -- a source code change within
Cyrus is not very likely. Is there a definition/description of the
sendmail interface somewhere (other than "the way Sendmail did it")?

Regards,
Sebastian
-- 
BlueMars - Gesellschaft für digitale Kommunikation mbH

Sebastian Maus            mailto:sebastian.maus at bluemars.net
System Administrator      http://www.bluemars.net/
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