Is Comcast controlling my email?

November 17, 2005 10:32 PM

Why do I have to use Comcast as my SMTP?

I own my own domain and use it for email. So, up until today, my SMTP in Microsoft Outlook has been set to "email.bradnelson.com" and worked like a charm. All of a sudden today, I couldn't send any emails from ANY of my email accounts in Outlook (personal and work). Turns out, I have to change my SMTP to smtp.comcast.net in order to send any emails.

Why do I have to do this? I don't really like the idea. What difference does this make?

posted by BradNelson to computers & internet (20 answers total)

not sure... i have comcast too and i use my webhost's SMTP server. seems to still be working.

you might check over at the dslreports.com forums and see if anyone else is experiencing this.
posted by joeblough at 10:39 PM on November 17, 2005

It might be that your mail server is down, although if both your personal and work servers don't work, that's probably not the issue.

My next guess is that it's a way of keeping spammers from using a Comcast connection to send out bulk mail (probably because of the high upload rates amongst other things).

You can try scanning the Terms Of Use, or if you're curious about their privacy policy, it's addressed here.

Other than that, it seems like your best bet would be to try the live chat or email feature at http://www.comcast.net/help/.
posted by spiderskull at 10:45 PM on November 17, 2005

Try changing your smtp port to 587
posted by meta87 at 11:04 PM on November 17, 2005

Comcast's policy is a spam prevention measure. The reasoning is: if all outgoing mail is required to go through comcast's server, then they can monitor outgoing message rates per IP address and track down zombies that are sending spam, or simply shut off IP addresses that exceed the rate limit. Also they can perform a degree of their own SMTP filtering to further detect and reduce spam. Whether this policy is effective over the long term is a subject for debate.

If you have your own domain, you should add SPF records to allow you to send mail on behalf of your domain using a comcast.net SMTP server. Many receiving mail servers perform this kind of check.
posted by ldenneau at 11:08 PM on November 17, 2005

My ISP blocks outgoing port 25 to "prevent abuse." The host for my personal mail (pair.com) has an SMTP server on both port 25 and 2525 to get around this restriction. Maybe yours does as well (or if you run your own server, change the port).
posted by helios at 11:15 PM on November 17, 2005

Yeah, I figured it's a way for Comcast to monitor what's being sent by their subscribers. I guess it's not a big deal, but it makes me slightly uncomfortable. (Oddly enough, I'm the last person to be worried about "Big Brother.")

My ISP blocks outgoing port 25 to "prevent abuse."
Hmm...definitely worth looking into.
posted by BradNelson at 11:25 PM on November 17, 2005

It's blizzocked.


Yeah, I figured it's a way for Comcast to monitor what's being sent by their subscribers.

i think more realistically, it's to prevent users from sending loads of bulk emails on port 25, potentially causing comcast port ranges to get blacklisted and using up bandwidth that they could otherwise shut down (i'm SURE they're metering your SMTP connects for abusive activity). Supposedly this also makes it just a little bit harder for folks to send to crapmail, as they can't do it directly from a comcast account.

I doubt but cannot discount the possibility that they are monitoring your mail.

FWIW many major providers are now doing this; SBC/Yahoo started doing this about 2 months ago (on residential accounts) and it confused the heck out of me, because we had one employee who kept complaining that he could check mail but not send it, and I *knew* our smtp server was working fine.
posted by fishfucker at 12:17 AM on November 18, 2005

er, ldenneau has a better phrased explanation that I managed to skip over. sorry!
posted by fishfucker at 12:19 AM on November 18, 2005

Just to chime in, Cox does the same thing with their cable services, for the reasons cited above: They don't want you sending out tons of mail (read: spam) on their internet connection. Especially in zombie mode.
posted by disillusioned at 2:27 AM on November 18, 2005

Actually, I sent it without the most critical piece of information:

It should make absolutely no difference at all.

I send tons of emails to clients and friends, through smtp.west.cox.net but using my domains and mail accounts, with no problems to speak of. They see them as coming from me@mydomain and would only be able to tell perhaps by closely examining the headers.

No worries, in the end.
posted by disillusioned at 2:28 AM on November 18, 2005

Once upon a time, I called up Cox and said "please re-enable port 25."

Within about 5 minutes, the call was escalated to someone who could help, and 5minutes later, all was well in the world.

Give it a try.
posted by mmdei at 4:50 AM on November 18, 2005

Who's your hosting company? Dreamhost allows SMTP thru Port 587, which in my case (RCN) isn't blocked. Give it a shot.
posted by rxrfrx at 5:19 AM on November 18, 2005

This happened to me with Comcast a couple of weeks ago. And then it resolved itself. Not sure why.
posted by yerfatma at 5:26 AM on November 18, 2005

I also use Comcast, and port 25 doesn't seem to be blocked here... yet, anyway. However, this may be something they're rolling out, as a lot of other ISPs have started blocking port 25. I used to work at a hosting company, and this caused us no end of headaches because a block of customers would suddenly experience mail problems, and usually expected us to fix them when their ISP was the problem.

If you have your own mail server, you can probably configure your Mail Transfer Agent (MTA) to accept mail on port 26 or another port that won't be blocked. Comcast is only looking for mail on port 25, which is silly and really doesn't stop spammers much at all.
posted by jzb at 5:29 AM on November 18, 2005

Yeah, I figured it's a way for Comcast to monitor what's being sent by their subscribers.

As fishfucker said, I don't think it is. It's to prevent a spammer's PC operating its own SMTP server, because without being able to connect to port 25 on third party servers, it's unable to drop off spam in other people's inboxes. Being unable to connect to your personal SMTP server is an intended (or maybe bonus) consequence.
posted by cillit bang at 5:36 AM on November 18, 2005

As fishfucker said, I don't think it is.

Poorly worded. I don't believe Comcast is reading my email, but only checking the volume of output.
posted by BradNelson at 7:29 AM on November 18, 2005

Not happening on my comcast connection, either.

I doubt that spammers sending mail via a 3rd party is a big problem, being as they already have access to that 3rd party machine. True, if they're finding open SMTP servers that shouldn't be. What they really don't want people to do and what spammers do is run their own server on their cable connection. But that's already hard to do because many mail servers are configured to refuse mail from obvious dynamically assigned IPs and/or domains.
posted by Ethereal Bligh at 7:59 AM on November 18, 2005

EB: I doubt that spammers sending mail via a 3rd party is a big problem, being as they already have access to that 3rd party machine. True, if they're finding open SMTP servers that shouldn't be. What they really don't want people to do and what spammers do is run their own server on their cable connection. But that's already hard to do because many mail servers are configured to refuse mail from obvious dynamically assigned IPs and/or domains.

True, but by blocking outgoing connects to port 25 they take care of both problems. And you only need one malconfigured relay or remote zombie to send out thousands of messages in an hour. When I was on the front lines of the spam war, I learned that "many" or "most" and $1.50 will get you a cup of cheap coffee. There are enough bad servers out there to make it profitable.
posted by KirkJobSluder at 8:25 AM on November 18, 2005

Why do I have to do this? I don't really like the idea.

Why don't you like the idea? Why do you even care? As far as I know or care, it's as meaningless as the difference between using the phone in your hall or the phone in your bedroom.
posted by AmbroseChapel at 1:56 PM on November 18, 2005

You care if the domain you use to send with is blacklisted on some spam lists. Or if one limits each email to something small and the other doesn't. Or if one is reliable and the other isn't. Or if one allows encrypted connections and the other doesn't.
posted by Ethereal Bligh at 2:52 PM on November 18, 2005