In general, this can't be done. There is nothing in the SMTP protocol
that carries any identification of the client OS. Depending on the MTA,
you can block attachments. You also can block by client's domain,
sender's domain, etc.
Jeffrey
Quoting Christian Klippel
hi all,
in hindsight of the current outlook worm, and the frequency in that these worms arise, i want to block any mail to my mailserver that comes from any ms software. currently im using qmail on suse 6.4. (yo, i know 6.4 is old, but it runs fine, so why update ? ;-) does anyone have experience how to do so ?? since im sure the time between new worms will get shorter and shorter, this is my "last solution" on my server for that.
greets,
chris
-- I don't do Windows and I don't come to work before nine. -- Johnny Paycheck