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. 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. I suspect you need to be looking at MUA <-> MSA <-> MTA handshakes and timeouts more than MTU sizes. 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 -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
