Brent Bloxam wrote:
> I'm trying to figure out how this issue is occurring and how to stop it. 
> Somehow messages are getting into our inbound Exim spool without any \n 
> at the end. When our outbound Exim process tries to deliver these mails, 
> they fail as Exim outputs '.' on the same line as the one it just sent. 
> I've verified this by capturing the SMTP conversation from both sides 
> with tcpdump
> 
> tcpdump shows the following being sent at the end:
> 
>> <!--www.https://example.com--><!--www.https://example.com-->.
> 
> Eventually the receiving MTA responds
> 
>> 421 Lost incoming connection
> 
> Passing the message in the spool through `od`, I see
> 
>> 0011700    e   .   c   o   m   -   -   >  
> 
> No \ns. These messages getting stuck in the spool seem to only ever be 
> spam. What I see in the outbound log,
> 
>> /var/log/exim/eximout.log:2009-12-21 08:00:00 1NLolk-0003aD-3V == 
>> [email protected] 
>> R=Storage T=Storage defer (-46): SMTP error from remote mail server after 
>> end of 
>> data: host 192.168.1.3 [192.168.1.3]: 421 mda.local SMTP incoming data 
>> timeout - 
>> closing connection.
> 
> Does anyone have any ideas? "message_suffix" sounded like it would have 
> been a good bandaid, but it only applies to appendfile and pipe.
> 

Where are these problematic messages originating?

i.e.

- local.  'non-smtp' on-box process? (less common, on-box smtp process..)

- smtp incoming from a(n alleged) peer MTA? (you mentioned spam..)

- AUTH'ed user with (compromised) MUA?


2 and 3 can be stopped easily in an ACL.

The first needs a bit more work - but very much worth it.

Once you block their arrival, all the other problems (queue, delivery) go away.

Bill

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