That's not the entire protocol capture- or if it is something is wrong. There should be a greeting from the receiver after the connection SYN-ACK, then the sender issues the HELO command. There should be a "MAIL FROM" and then a "RCPT TO" command issued:
From what I can see here nothing would get delivered since there is no email header sent. You might need be getting any errors because there is not enough for the mail server to determine whats wrong (so it fails silently). The best way to test would be to use a properly constructed message or even better just use a sniffer to monitor the conversation between your mail server and comcast. Any possible security (i.e. is your IP blacklisted?) or protocol issues should be present in the conversation.
If you're familiar with
wireshark you can use that to filter by right-clicking on any related packet and choosing "follow tcp stream" to reconstruct the message so that you can read it.
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Keith C. Perry, MS E.E.
From: "Carl Johnson" <cjohnson19791979@gmail.com>
To: "PLUG" <plug@lists.phillylinux.org>
Sent: Tuesday, September 30, 2014 4:39:12 PM
Subject: [PLUG] msmtp looks like it works.....
but it really doesn't. Is anyone sucessfully using this with a comcast account by chance?
--> DATA
<-- 354 enter mail, end with "." on a line by itself
--> hello.
--> .
<-- 250 2.0.0 xYW41o00M38PZeL01YW562 mail accepted for delivery
--> QUIT
<-- 221 2.0.0
resomta-po-02v.sys.comcast.net comcast closing connection
.......... but nothing ever arrives on the receiving end. I've already verified that I can send/receive mail to and from both accounts, both directions, using other means.
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