How to show evidence to the ISP
 

Dear All,

I am facing with a problem of mail lost.
When passing through a certain MTAs,
emails with attachments will be blocked.
If there is no attachment, the emails can
pass through successfully.

I need to show the evidence to the ISPs
that their MTAs block my emails. What should
I do next?

Any suggestions, please let me know. Or
if anyone has solution to my problem, please let
me know.

NOTE: my home mail server is RH9, SENDMAIL 8.12.8-5.90
as the MTA. Already used telnet ... 25 it and it
function normally.

Some ISP are setup in a way that their customers can not send using outside or inside e-mail servers. This means you have to use your ISP e-mail servers to send the e-mail. I have to use my ISP e-mail servers to send all my e-mail accounts except for HTTP e-mail accounts.

Have a look at your SENDMAIL logs. Your SENDMAIL logs is the only information that you have. Many servers are setup in a way to block any e-mails with viruses or files that might contain viruses. Try to attach none compressed files or executable files. Keep attachments smaller than 1 megabyte or 500 kilobytes.

You may have to read your ISP policy on e-mail.