In een bericht van 14-9-2016 5:11:
By "message" do you mean an actual piece of email reporting the problem or a notification in the Thunderbird user interface?
I mean indeed by Thunderbird.
Email messages reporting a delivery failure are almost always generated by some MTA, e.g. Postfix. There's a standard format for such failure report messages that most MTAs use which includes an explicit "Reporting-MTA" field identifying the generator of the report. A "message" from the TBird UI (i.e. an alert window or error message in a status area of the main widow, etc.) is almost certainly generated by TBird itself. The first step in submitting a message is the MUA (TBird) saying "EHLO <hostname>" to the MSA/MTA (Postfix) and getting a response listing the supported extensions to SMTP supported by that server. Example:
Thanks for your exented info on this.
passed along from that external program. For example, I use code run via the MIMEDefang milter to impose smaller limits on some sender/recipient combinations which can reply with text saying the message is too large. In that case, Postfix is sending an explicit rejection response to the client and it is up to the client to relay that back to the user.
So I need to install the MIMEDefang milter to get what I want or do I misunderstand you?
Cheers, Jos Chrispijn
