email issue - sending To: Comcast

[Allodoxaphobia]

Starting yesterday, my ISP SysAdmin tells me that emails being sent To:
Comcast email addys from his system are encountering a timeout while
connecting to the Comcast servers.

His comment and an example:

"... They are in the deferred queue because Comcast is timing out. I'm
not sure why. Here's an example of one of your tests:

0733BCE044 560 Sat Apr 17 01:23:32 From:email...@example.net
(delivery temporarily suspended: conversation with
mx1.comcast.net[96.114.157.80] timed out while receiving the initial
server greeting)
w3...@comcast.net "

Sure enough, all my tests to my primary and secondary email addys at my
Comcast account are never received by the account. And, a purposefully
non-existent email addy @comcast.net does NOT serve up a bounce.

Anybody else seeing something like this?

Thanks in advance,
Jonesy
--
Marvin L Jones | Marvin | W3DHJ.net | linux
38.238N 104.547W | @ jonz.net | Jonesy | FreeBSD
* Killfiling google & XXXXbanter.com: jonz.net/ng.htm

[VanguardLH]

Allodoxaphobia <trepi...@example.net> wrote:

> Starting yesterday, my ISP SysAdmin tells me that emails being sent To:
> Comcast email addys from his system are encountering a timeout while
> connecting to the Comcast servers.
>
> His comment and an example:
>
> "... They are in the deferred queue because Comcast is timing out. I'm
> not sure why. Here's an example of one of your tests:
>
> 0733BCE044 560 Sat Apr 17 01:23:32 From:email...@example.net
> (delivery temporarily suspended: conversation with
> mx1.comcast.net[96.114.157.80] timed out while receiving the initial
> server greeting)
> w3...@comcast.net "
>
> Sure enough, all my tests to my primary and secondary email addys at my
> Comcast account are never received by the account. And, a purposefully
> non-existent email addy @comcast.net does NOT serve up a bounce.
>
> Anybody else seeing something like this?
>
> Thanks in advance,
> Jonesy

Any e-mail provider can establish blacklists or employ gray listing
against untrusted or suspicious e-mail sources. At times, Hotmail was
blacklisting Gmail, and visa versa. I use Spamgourmet (SG) for
on-the-fly e-mail aliases, and sometimes e-mail domains reject e-mails
from SG because they can be abused by spammers (although the SG operator
is very responsive to abuse reports to kill the bad aliases). At times,
Hotmail or Gmail were rejecting e-mails aliased through SG.

Greylisting works by rejecting the first SMTP submit and requiring the
sending SMTP server to resend the same message. Spam servers don't
resubmit: they puke once, and move on to process the rest of their
mailing list.

https://en.wikipedia.org/wiki/Greylisting_(email)

Also, there is flood control. If volume suddenly increases from a
source, the receiving SMTP server can reject or greylist the source.
You didn't bother to mention who is your ISP providing the e-mail
service for your outbound e-mails. There are online stats showing the
e-mail traffic volumes for various providers, and that would indicate
what would be an expected volume from those sources. A volume that
suddenly jumps is seen as a spate of bulk or spam e-mails. Your ISP
e-mail admin should be able to see what has been their history of volume
to determine if there has been a sudden outbound flood.

Another anti-spam filter is how many invalid e-mail targets are
specified by a source. Spam uses mailing lists, and a lot of those
entries are invalid. They are generated lists trying to hit lots of
e-mail targets (accounts) whether they exist or not. That's why
spammers love when you attempt to unsubscribe, because that identifies
they hit a valid and monitored target -- something very valuable to
them. But they also spew to lots of invalid targets which result in NDR
(Non-Delivery Reports) from the receiving SMTP server. When a threshold
is hit on too many NDRs, the receiver considers the sender to be
flooding or spamming due to all the invalid e-mail addresses.

That outbounds are timing out (rather than simply getting rejected)
implies the receiving SMTP servers are too busy, getting flooded or
DDOS'ed, down for maintenance, or they employ greylisting and your ISP
is puking out way too many e-mails to Comcast, not retrying the pending
submits, or not waiting longer than the greylisting timeout.

While your sending SMTP server (for your ISP) might be directly
connecting to Comcast's SMTP server, it could also be the e-mails are
routed through another intervening SMTP server. Could be the hop to the
intervening SMTP server is the problem. You'd have to ask your ISP if
they are directly connecting to COmcast's SMTP server, or routing
through an intervening SMTP server. Also, your ISP may not be providing
their own e-mail service, but contract it from someone else. For
example, a lot of companies that profess to have e-mail actually
contract it with Yahoo, Gmail, or another e-mail provider. They may
even have their own domain in their e-mail addresses, but they don't
actually have their own e-mail servers.

You make no mention how long this timeout has been happening. Is it
something that showed up in the last hour, in the last few hours, for
days, weeks, months ... how long? No idea how many retries your ISP
uses for sending outbound messages. Because networking, hops, or
services can go down temporarily, and e-mail server should retry sending
an e-mail, but it's up the admin to decide how many retries and how long
to wait between retries. Has this problem existed for more than a day?

I just did a test. Send a test e-mail from Hotmail to Comcast. E-mail
showed up immediately at Comcast (under 1 second by looking at the
datestamps in the Received headers). Send a test e-mail from Gmail to
Comcast. I noticed the test message hung in the Outbox folder for
almost a minute which means Gmail was slowed in sending to Comcast.
After waiting 10 minutes, I gave up waiting for the test message from
Gmail to show up at Comcast, and sent another test message. The 2nd one
showed up in my Comcast account. Don't know what happened to the 1st
one. According to the Received headers, the test message from Gmail to
COmcast took under 1 second to arrive. You never mentioned who is your
ISP to know whose e-mail service you might be using. Someone using THAT
e-mail provider, and Comcast, can test if there is a delay for their
e-mails to arrive at Comcast. If immediate for them, could be you are
on Comcast's spam blacklist. If it is working only now, it was a
transitory problem with Comcast's SMTP server for which you didn't wait
long enough to see if it went away. My tests were over 7 hours after
your posting here.

You are NOT sending from example.net as shown in your copy of the status
message. So, just WHO is your ISP whose e-mail service you are using to
send e-mails to Comcast? Is it still a problem NOW?

[azigni]

Perhaps you should try:

https://www.xfinity.com/support/contact-us