maybe OT - sendmail+outlook problems

[Wojciech Puchar]

while i use sendmail for many years and many of my users have outlook 
express (it's their problem not mine, there are lot of normal mail clients 
available for windows) and all works.

recently i installed sendmail as one of server programs when configuring 
machine for someone (standard "delinuxation" procedure). his users started 
complaining about problems with sending mails. no problems happened when 
receiving mail.

while lot of his users use outlook, only part of them complains, but i've 
seen it live.

when outlook starts to send large mail, it sends first few MB then chokes. 
sometimes it unchoke and send more data, chokes again etc.
sometimes it says that server didn't respond for too long time and aborts.

on server i started trafshow and it showed everything normal, but when 
"choking" it showed transfer speed of about 2-3kB/s.

there is no problem with cables, switches etc. as ftp sessions goes full 
speed always both to and from server.

all windows firewall was turned on or off when testing and it doesn't 
change anything.

position where it chokes is random.

tested using pine on other machine (pine was set to send directly through 
this sendmail) - no problems with 50MB mails, tested many 
times.

while i have network for over 300 users, maybe 20% of them using outlook 
(those who refused to use thunderbird we install when connecting), but 
none complained.


could You please give me any quirk about what to check more and find the 
reasons why it happens?

his network has separate machine (still running linux now) designed for 
traffic control. but traffic control rules are not port-based, and for 
sendmail server there are no control just routing.
can linux make such problems? i don't think so as FTP goes fine, but just 
asking.