> Getting a lot more cases of timeout after DATA..
We see these too. They're usually slow senders who are not
exceeding our timeout settings, so my guess is that many of them may
have a shorter timeout setting on their systems.
> Seems they send the DATA, but after this we don't see any QUIT issued..
> well, at least not until the timeout on connection expires.. It's after
> we send the 250 OK in response to the DATA..
Once your systems sends them that 250 response, then that signifies
that you're taking responsibility for the next stage of delivery. In
a perfect world the QUIT command will follow (or RSET, etc.), but
since the possibility of a legitimate connection termination is not
non-existent, it's best to rely on the 250 status as confirmation...
> Just curious.. Are they just terminating without sending waiting for the
> OK, or just sending the QUIT?
Senders are supposed to wait for a 250 or other response (e.g., a
failure). If your mail server software can check for a terminated
connection before sending 250, then you can just discard the message
if they've disconnected (because it's reasonable to assume that they
will re-send if it's important).
So, if they keep disconnecting from systems before the DATA stage
completes, and they're in spam blacklists, then it should be fine to
just block them (or permanently feed them 4yz error codes whenever
they connect).
--
Postmaster - [email protected]
Randolf Richardson, CNA - [email protected]
Inter-Corporate Computer & Network Services, Inc.
Vancouver, Beautiful British Columbia, Canada
https://www.inter-corporate.com/
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