Re: [exim] Error relaying large emails over two exim hosts

> <div class="moz-text-flowed" style="font-family: -moz-fixed">OPTITAS
> Info wrote:
>> Environment (all servers running Debian etch w exim4 and latest
>> patches applied).
>> Both Linux-Servers are running FWBuilder iptable firewalls.
>>
>> Scenario sending a mail from the WXP PC:
>> * WindowsXP-PC w Thunderbird (eMail source)
>> -> MailServer1 (gateway, smart router, connected via DSL Router)
>> -> MailsServer2 (relay, outgoing eMail) sending emails to the final
>> destination.
>> Anything works fine until large eMails (or eMail w large attachments /
>> approx > 1MB) are sent.
>> Whenever large email are sent, the connection once is broken and the
>> sending host (Server1) retries sending the emails on next
>> queue-run.
>>> From the exim log of Server1:
>> "R=smart_route T=remote_smtp defer (-46): SMTP error from remote mail
>> server after end of data: host xx.xx.xx.xx [xx.xx.xx.xx]: 421
>> adomain.eu SMTP incoming data timeout - closing connection"
>>
>> I did some investigation a few weeks ago and found out that after a
>> while fragmented packets are sent over the Internet line. I
>> tried some "optimized" MTU settings but could not solve the problem. I
>> do not think it's a problem with the MTU.
>>
>> Regardless of the problems sending large mail from Server1 to the
>> internet, receiving large eMails is not a problem.
>>
>> Any help appreciated.
>>
>>
>
> Sounds as if the two LinBoxen involved are under your control.
Yes.

>
> If so, what happens when you scp or ftp comparable sized files between
> them over the same links & via the same firewalls (if any)?
>
> My guess is that it is trouble-free.
You are right!

>
> I suspect you need to be looking at MUA <-> MSA <-> MTA handshakes and
> timeouts more than MTU sizes.
Could you pls. tell me which timeouts - related to the exim configs - need to be changed?

Regrads
Tilman
>
> JFWIW, we limit to 800 MB - enough to handle a full CD plus transmittal
> notes.
>
> Initially, we did have to adjust time-outs ELSE sender's MUA was unaware
> it had suceeded, made multiple successive deliveries.
>
> Attachments of several MB are common, and no trouble.
>
> CAVEATS: *BSD servers, ABM desktops, SeaMonkey MUA.
>
>
> HTH,
>
> Bill Hacker
>
>
>
> </div>
>