there is no errors on log files,
the log files doesn't have any lines refferred to the outlook connections,
but I see a lot of TIME WAIT in netstat on tcp6.
I think that some version of outlook uses ipv6 connection, and I guess this is the problem, but I don't be able to solve it.
The problem is only in some outlook windows versions,
for the Mac users and other windows users the emails works fine.