Archived from groups: microsoft.public.windowsnt.protocol.tcpip (More info?)

Hello all,

Trying to decode TCP/IP packets coming across port 25 (email). Am having
good success, except for Webmail traffic, which sometimes uses port 80.
Sniffing shows Webmail headers and footers come across port 25, but the
Webmail body comes across port 80.

In other words, emails coming from Microsoft Exchange are easy (port 25
only), but emails coming from Google's GMail Webmail, for example, use two
ports: 25 and 80.


Questions:
What is the email command (SMTP or other) that says, "stop listening to
port 25 and switch to port 80 for awhile." Then, there must be an opposite
command to "switch back to port 25."

Can someone point me to documentation, including commands/record layouts,
that explains this? Sample code would be optimal.

Thanks!

Paul