[SOLVED] majordomo and DMARC

scasey · 05-23-2017, 12:50 PM

I have a production server using majordomo for mailing lists. Recently, I've noticed that email from subscribed list members at AOL is being rejected because of failing AOL's DMARC checks. This happens on deliveries to AOL, Yahoo!, Hotmail, MSN, and a few others.

The failure messages suggest that the From: header needs to NOT be aol if the mail is not being delivered by an AOL server, which of course, it is not. The "fix" is to set the From: to be the list address, and the Reply-to: to have the aol address.

Unfortunately, changing the From: is not readily configurable in majordomo. I have figured out a patch to majordomo's resend script and will be happy to share it if there is any interest here.

I have started another thread to discuss DMARC-compliant mailing list managers.

quilliw · 07-10-2017, 12:35 AM

Quote:

Originally Posted by scasey

I have figured out a patch to majordomo's resend script and will be happy to share it if there is any interest here.

Yes, please do.

scasey · 07-10-2017, 05:18 PM

Sorry, I know how to apply patches, but not how to create one.
These changes will
1) Capture the To: address (the list address) and
2) Change the From: address to be the list address prior to sending the email.

This prevents AOL, Yahoo, and ?? from rejecting the message because the From says aol.com, but the email is not coming from AOL.

Add the blue lines to resend at the indicate places.

Code:

in resend after line 353... 
#
# Message parsing starts here
#
## First get the "To: and capture the address... DMARC adds
print STDERR "$0: find To:.\n" if $DEBUG;
while (<IN>) {
	## added to capture the list address for use as From; 'cause of DMARC stuff.
	if (/^To:\s*(.*)/i) {
		$newfrom = $_;
		print STDERR "$0: New From Before $newfrom\n" if $DEBUG;
		$newfrom =~ s/^To: //;
		print STDERR "$0: New From After  $newfrom\n" if $DEBUG;
	}
}	
close(IN);

open(IN, "$TMPDIR/resend.$$.in") || 
    die("resend: Can't open $TMPDIR/resend.$$.tmp: $!");
###  end of DMARC changes


print STDERR "$0: parsing header.\n" if $DEBUG;

# parse the header for bad lines, etc.  We'll bounce in a moment.

Code:

in resend after line 512
# spit it out!
#
while (<MAILIN>) {

	## Change From to value of To (in $newfrom) 'cause of DMARC 
	if (/^from:\s*(.+)/i) {
		### change from to value of To: 'cause of DMARC...
		print STDERR "$0: before From: $_\n" if $DEBUG;
		$_ = "From: $newfrom";
		print STDERR "$0: after From: $_\n" if $DEBUG;
	}



    print MAILOUT $_;
}

# cleanup
#

Then go to the config for each list and set the reply_to to $SENDER, because the From address will no longer show who sent the email.
I'm open to any cleaner solution or a DMARC compliant mailing list manager.

Let me know of any questions/concerns.

quilliw · 07-11-2017, 11:03 AM

Quote:

Originally Posted by scasey

Sorry, I know how to apply patches, but not how to create one.

That's easy, really: You use the "diff" command, I like using options "-pub" which will give you, in order, the function/block the change happens, unified diff format, and ignore whitespace changes. The attached patch has been created with

Code:

diff -pub /usr/lib/majordomo/resend resend > patch.txt

Quote:

Originally Posted by scasey

Then go to the config for each list and set the reply_to to $SENDER, because the From address will no longer show who sent the email.
I'm open to any cleaner solution or a DMARC compliant mailing list manager.

Let me know of any questions/concerns.

It's perl so there will be more ways to do it.

I might add another option to resend so I can enable it per list. I'll update here if and when.

scasey · 07-11-2017, 01:05 PM

Cool, thanks for the lesson! I did use diff to find/remember where I'd made the changes, but didn't know that was how patch files got built.