On 9/21/20 10:49 AM, peterbw@gmail.com wrote:
Hi,
We've recently noticed an issue where users who are cc'd in a message where a mailing list is also within the cc list are getting rewritten a user@invalid.domain.
This issue looks like it may be related to Outlook and how user names are displayed specifically. Here is an example:
To: test_user@gmail.com cc: listserv@lists.test.org; Williams, Peter;
"Williams, Peter" maps to a user e-mail in the Outlook Global Address book. When the message is sent the list will send the message with the first name and last name separated, for example the message will appear:
to: test_user@gmail.com cc: listserv@lists.test.org, Williams@invalid.domain, Peter@invalid.domain
Because apparently Outlook is sending the message with the literal
Cc: listserv@lists.test.org; Williams, Peter;
instead of something like
Cc: listserv@lists.test.org, "Williams, Peter" <peters_real_address@example.com>
Then some MTA in the chain is seeing the unqualified addresses Williams and Peter and appending its own local domain.
This only seems to happen with users who are cc'd who are also members of the list that is being cc'd. For example in the scenario above my e-mail that is cc'd is also a member of listserv@lists.test.org.
In this case, where do you see this? i.e., do other list members see it in the message they receive from the list?
I don't know why that would be. I'm certain that Mailman is not involved in this and the Williams@invalid.domain and Peter@invalid.domain addresses are in the Cc: as received by Mailman.
This issue does not occur if the user e-mail address is listed before the mailing list in the cc field. So for example, if the cc in the scenario above contained Williams, Peter; listserv@lists.test.org; it would route properly.
Again, I think this is Outlook.
What's in the Cc: of the mail that test_user@gmail.com receives directly?
What happens if you send mail in this way with
To: test_user@gmail.com cc: other_user@gmail.com; Williams, Peter;
Again, what's in the Cc: of the mail that test_user@gmail.com and other_user@gmail.com receive?
Also, please see <https://wiki.list.org/DOC/Mailman%20is%20not%20Listserv>.
-- Mark Sapiro <mark@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan