Question : timeout waiting for input during message collect

hi,

im running sendmail 8.11.6 in a RH72 linux server.

recently i changed the ip addresses of our servers and right after that
outlook clients started timing out when sending a message to sendmail.
they start the transfer, sometimes reach about 50% and then timeout after 60 seconds (default timeout).
e-mails without attachments do get through sometimes.
e-mails with attachments 50Kb + timeout most of the times.

sendmail log shows a "timeout waiting for input during message collect" which
means both sides are unable to complete the process.

every word i found regarding this problem points to a network/connectivity
problem but i think this is not the case.

as a workaround i changed the MTU of the local interface to 500 (instead of
the default 1500) but outlook still have problems sending email.
emails with attached files just cant pass through.

i dont have any other client software to test here, but i also dont think
it is a specific outlook-sendmail issue.

since the problem started the same week MyDoom made his debute i thought
it could be a virus related network problem - infected workstations could
cause a network overload and prevent normal traffic from getting its share
of the link.

today i ran netstat and there were no smtp connections apart from the one i
started to run my test. I mean, sendmail was not busy receiving/forwarding
anything but my own request.
also, all other network related activities (ftp, http, file transfers) are
ok - e.g - i can ftp a file from the same server at 10 mbps (yes, we use 10 mbps ethernet cards).

any ideas ? any other relevant info i should check ?

ty

Answer : timeout waiting for input during message collect

It's not easy to do with a "bare sendmail", but fortunately there's an excellent anti-spam/anti-virus filter that can do exactly that. I run MailScanner (http://www.sng.ecs.soton.ac.uk/mailscanner/index.html) on all of my mail servers and allow it to scan everything that reaches the mail server. Not only will it block all of the "dangerous attachement types" out of the box, but you can add commercial virus scanners (it supports every one that will run on Linux) or the OpenSource ClamAV scanner. And as a bonus you get spam filtering via SpamAssassin.

I don't like the way Julian (MailScanner author) sets up MailScanner on a Linux system, so I've worked out my own procedure for installation. You can see how I do it at  http://www.entrophy-free.net/anti-spam.html My document is a slightly behind w/respect to the MailScanner version, but the procedure is the same.