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I’ve had my share of issues with Comcast in the past, and this one is just as frustrating.

Just like many of my issues with them so far, it’s completely inconsistent from market to market, so their support department seems to know nothing about it.

Anyone hosting their own domain somewhere, yet having Comcast as an ISP is continually being forced to jump through new hoops in order to send mail from their own domain.

Until now these hoops have been to verify your outgoing mail settings and change your SMTP port to 587 (or another port for your local market).

Now there’s another inconsistent change that’s not affecting everyone.

As a Portland web host we have three mail servers that our clients use,  and for the past three days, all users that are on our #1 server are unable to send mail to other Comcast addresses.

To make matters worse, Comcast is then misreporting the problem, sending the end user a link, where their page says that their mail server is “blocked as spam”. (For the record, this mail server is not on any spam blacklists at this time).

So, now we are forced to explain to each complaining customer that this is some sort of problem or mistake on Comcasts end, AND we then have to explain that Comcast is also showing them incorrect information.

I have verified that even when you change to port 587 for your outgoing mail server, if the address you are sending to is another Comcast address, then the mail bounces back with this message –

<[email protected]>:
Connected to but greeting failed.
Remote host said: 554 comcast Comcast block for spam. Please see

This message says that our mail server ( has contacted the Comcast mail server, who is blocking the message as spam. WRONG.

Visiting the link is of no use to the end user, but as the server administrator I was able to follow the directions and submit our removal request at as directed.

Imagine my surprise when I got this e-mail back –

Thank you for contacting Comcast Customer Security Assurance. We have received and reviewed your RBL removal request.

Below each IP address you submitted in your request, we have included the result of our research. Please do not reply to this message.

Your request for IP block removal has been denied for the following reason:

– You have been blocked from emailing the Comcast network because we have determined that you are sending email from a dynamic/residential IP within the Comcast domain.

Comcast does not allow subscribers to send email from a mail server other than All mail should be sent through Comcast’s mail server.

For information on configuring your machine to use, please follow the link below.

If you need to run your own mail server, please contact our Commercial Services organization at [email protected]

Comcast Customer Security Assurance

Did you note the bolded statement that “Comcast does not allow subscribers to send email from a mail server other than” ?

If that’s really a policy, then why is only ONE of our mail servers affected, and then, only for mail which is sent to other Comcast email addresses?

Do you suppose this is just a mistake by a server administrator who misunderstood the direction he was given?

Or, do you think they were really told to block all outgoing mail from any servers other than their own, and that the change outbound port 25 to 597 fix will no longer work soon?

If you are suddenly having this problem here is a workaround to fix it:

Open your e-mail program and change your outgoing mail server from (Screenshots are from Outlook 2007, another nightmare)

Change Outgoing SMTP – and go to “Advanced”


Be sure to CHECK THE BOX (or leave checked) – My outgoing Server requires Authentication”

Then change to “Verify using” and type in your comcast username and pw


In order to get this working, you MUST ALSO change your outgoing computer port to 587 – So I THINK they’ll be screwing this up too.


WTF is going on, Comcast?

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