port question

[Tony Alfrey]

Since we're on this topic perhaps someone can confirm/deny my conclusions:

1.  An SMTP *client* within a mail client such as Thunderbird, sends 
outgoing mail to an SMTP *server*.  Correct?

2.  That SMTP *server* may then send mail to a receiving SMTP server 
(via the internet or other network).  Correct?

3.  The SMTP *client* in (1) sets a port within the TCP/IP protocol 
packets of the outgoing mail.  If Port 25 is set, it may be rejected by 
the outgoing SMTP *server*, and never re-sent (relayed).  Correct?

4.  The receiving SMTP server may also possibly reject Port 25 if sent 
by the transmitting SMTP server.  Correct?

5.  An ISP used by a mail client to reach an SMTP server may reject Port 
25 packets.  These packets may never even be seen by the first SMTP 
server intended for sending the e-mail.  Correct?

In other words, there are several places where Port 25 may be blocked by 
many SMTP servers or ISP that may lie between a user e-mail client on a 
home machine (an SMTP client) and an eventual SMTP server used to 
receive, and store, email for the intended recipient.  Correct?

Thanks very much!

-- 
Tony Alfrey
tonyalfrey at earthlink.net
"I'd Rather Be Sailing"