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Doug Kaye’s Weblog

1/17/2008

Blocked by Comcast

10:01 pm

Starting early this morning I was unable to send any email from my Mac. Late this afternoon, my wife said she had the same problem. I did some testing and determined that I couldn’t send to any SMTP host (not just Comcast’s host) on port 25. I could send email from my Gmail account, but that’s browser based. I did a little surfing and found a thread on Chris Pirillo’s site in which others have had the same problem.

It turns out that Comcast has blocked my outbound traffic to port 25 on any server. Did they inform me? No. Was there a reason for doing so? No. I use the smtp.comcast.net server for outbound mail, as they told me to when I signed up for their service years ago.

I called Comcast support and spoke to a useless tech. He said I should call Apple because there must be a problem with my Mail program. Oh, and my wife’s, too, of course. But the Lockergnome thread suggested I call Comcast’s security department at 856-317-7272, which turned out to be a good idea. The first thing the automated system tells you to do is go to www.comcastsupport.com/alternateport and download the OneClick fix. Okay, except it’s specific to Outlook Express. Doh! Another call to the security guys to talk to real people. These folks at least know what they’re talking about, and I was able to get back up and running.

Apparently, this is part of some ongoing program. Comcast disables outbound traffic to port 25 at the drop of a hat. Other ISPs do this, too, although I would hope they’d communicate first with their customers. The fix?

  1. Configure outbound email to smtp.comcast.net, but on port 587, not the default port 25.
  2. You must use password authentication for outbound/SMTP. Unless you’re using your ISP’s web mail, you probably forgot your username and password, so you’ll have to call the ISP to get them.
  3. Do not use SSL.

Alternatively, just do what so many people are doing and use Gmail.

31 Comments »

  1. I first wrote about this as well back in September of 2006 twhere I also included a list of known providers who where doing this

    http://www.winextra.com/2006/09/18/gotta-love-bellnet-not/

    Comment by Steven Hodson — 1/18/2008 @ 12:16 am

  2. Is it supposed to be an anti-spam/anti-bot measure? If so, why not just demand authentication for outgoing mail? It’s a shame when Internet Service Providers stop providing certain Internet Services.

    Comment by Derek K. Miller — 1/20/2008 @ 2:09 am

  3. Blocked by the web…..get used to it..work on bandwidth penetration..for the good of all who have something to say.

    Comment by Jim Berkke — 1/28/2008 @ 5:02 pm

  4. First…let me fix my spelling sorry. My ISP (hughes.net a satellite ISP) cuts us down all the time. Even though there is lighted fiber .25 miles away I can’t tap in! Go figure.

    Comment by Jim Brekke — 1/29/2008 @ 8:12 pm

  5. I am extremely steamed at Comcast. Sure, the port 587 is ok if you just use an email client…but my old Ricoh 4410NF fax won’t use any other port for scan to email…so Comcast has left me with an $1800 boat anchor. They first lie to me, tell me they don’t block the port, then they admit and say sorry…we will fix it…then they don’t! I am totally sympathetic to blocking spam, but my machines are no bots. I scan ‘em and clean ‘em often. Looks like I need a new ISP… Any suggestions out there?

    Comment by Chuck Heubach — 1/31/2008 @ 8:42 pm

  6. a way round this is to use your own internal company gateway to send email through your gateway to your remote mail service through a hosted website. ie my company host corporate sites and we do this for our customers. 404 474 3023

    Comment by Kevin Kirton — 2/28/2008 @ 7:57 am

  7. Kevin - Comcast is blocking all traffic outbound on port 25 (and maybe inbound?) on every residential account I’ve come across in the past several months. While this may not matter to most people, it causes huge problems for others. :-(

    Comment by Good ol' Comcast — 4/21/2008 @ 7:52 am

  8. They hit me with this just recently. Claimed I sent out spam mail, but I’m guessing it was someone else at the same floating IP. ‘Their’ notification mail had misdirected links in it, and while trying to find out if it was a phishing attack or not, I got nothing but a runaround from their ’security’ section via email. Thanks for summarizing the problem; changed the port in Thunderbird, and things work fine (I’ve always used auth).

    Comment by Comcast...sigh — 5/3/2008 @ 5:36 am

  9. Thank you guys! I swear I thought I was loosing my mind. I had just added my second Slingbox to my router and recently downloaded BitTorrent…I was lost as to why suddenly I couldn’t send e-mails after it worked so perfectly for 2 years. Thanks for the info, e-mails are now sending perfectly.
    So if I’m reading everyone correctly, Comcast is doing this because we are “sending spam”??? Not one of my machines!

    Comment by Patch Landers — 6/2/2008 @ 4:58 pm

  10. Good Stuff here. Thank you for the tip. Works great.

    Comment by Anonymous — 6/19/2008 @ 7:17 pm

  11. Love this - the way they told me about their change here in DC by telling me I have a virus. Nice…

    Comment by ajawamnet — 6/26/2008 @ 6:59 am

  12. Thank you so much for the solution. I thought there for a second there was something wrong with the data I inputted into my program so I did a search on the web for the info and I came here.

    Comment by Darkside — 7/9/2008 @ 4:32 pm

  13. What happens when you set it up this way and take your laptop on the road? Will you still be able to use the comcast server on 587 from a hotel?

    Comment by Mike — 7/13/2008 @ 7:27 am

  14. Have any of you filed a complaint with the FCC? Nothing will get changed until the people with the big hammer are notified. The FCC is already investigating Comcast and have found them lacking. Now’s the time to make your displeasure known.

    Comment by Richard — 7/18/2008 @ 9:07 am

  15. Bastards. If they are right, and I was sending spam via a bot, then this is the first recorded occurrence of such a bot on a Mac. I don’t buy it. I think they’re just running a crappy service.

    Comment by Dave — 7/23/2008 @ 11:36 pm

  16. Thanks for the instructions; that fixed my problem. I hadn’t been able to send mail all week and couldn’t figure out why.

    Comment by Lauren — 8/7/2008 @ 4:17 pm

  17. thanks for the help but this still hasn’t fixed my issue with comcrap email. i called their tech support which was as useless as they come. the guy was trying to tell me my outlook was setup wrong. funny how it’s been working with SSL for a couple years now and just stopped.

    i just tried to call 856-317-7272 so apparently they know about it because the automated system said if u r a comcast customer press 1, if u r having email issues press 1, if you can not send email press 1, we r now closed. grrrrr comcrap

    Comment by bas — 8/11/2008 @ 9:18 pm

  18. One more step may be needed. I had the identical problem, which also was resolved by calling the security department (after hours of nonsense from other personnel, including ” we don’t allow customers to send email with their own domain any more”. I use Eudora 6.2 with Max OSX 10.4.x, comcast, netgear hardwire/wireless combo router. The router is firewalled.
    The comcast security 888-565-4329 said they would lift this one time only, even though there was no evidence of any problem with any of my domains.
    They required: - firewalled router (yes), port 587 (some other options too, as long as it’s not port 25) which I had checked as yes, and smtp authentication- yes.

    I was still getting an error in eudora though. This was fixed by going to my cpanel where I host my domains, and adding port 587 to the web host manager. see http://webmastersedge.net/home/2008/cpanel-tutorial-opening-up-another-port-for-smtp-when-port-25-is-being-blocked-by-your-isp/ for additional information about Setting Up Exim To Listen On Your Chosen Port.

    Comment by Christine — 8/14/2008 @ 5:16 pm

  19. The fix worked for me.. Thanks

    Comment by Tyler — 8/20/2008 @ 3:12 pm

  20. This fix worked for us too. Comcast is horrible, wish there were alternatives in our area. THANK YOU

    Comment by DBB — 8/23/2008 @ 7:42 am

  21. Thank you

    Comment by Patrick — 9/8/2008 @ 11:47 am

  22. Thanks for posting this - I have just been having this problem over the past week. Your suggestions fixed everything!

    Comment by Jason — 9/20/2008 @ 1:40 pm

  23. I,ve been fighting this for two friggin weeks - it worked on port 25 one day then poof! I made the port change and allow authentication. Works fine. BTW my iMac MAIL was okay.
    Pragmatic JIM

    Comment by JIM HELMS — 10/4/2008 @ 10:23 am

  24. Yep scumcast got me with this a few weeks ago. I’d been using the same email config for almost 3 years without any problems and then suddenly *poof* can’t send email. Had an interesting conversation with their helpdesk where the oper insisted that I couldn’t have been using port 25 and that the server I was connecting to at my workplace didn’t use that port. Even after I informed him that I was the person that built it……..

    Comment by Jim Angell — 11/4/2008 @ 7:45 am

  25. 3 tech reps later & I end up at Microsoft Outlook Express drooling for $49.00 which they won’t charge if they can’t fix it. Well, guess what, it’s not Outlook - it’s Comcast & the morons at Comcast can’t fix it… Ad I thought I was heading up the ladder to a higher tech ground, all of a sudden I was speaking to a Microsoft office in India… Great world we live in. Still can’t send out mail thru my company server.

    Comment by Anonymous — 11/4/2008 @ 8:39 am

  26. Thank you for your help.

    Comment by Albert Feliz — 11/11/2008 @ 9:47 pm

  27. Thanks this worked for me, BTW I had to add one thing since I am using comcast’s smtp for other mail addresses I had to added my comcast authentication info too.

    Comment by Dennis — 11/14/2008 @ 2:34 pm

  28. They (Comcast) screwed me as well. My company laptop is setup through our company ISP and that email account uses port 25. They wouldn’t release it for me, and now I have to contact my company ISP and try to get another port. I hope no friends or family ever want to email from my house via wireless. I don’t fell I’m getting 100% internet service anymore, I may stop paying 100% of the bill.

    Comment by Jeff Tucker — 11/15/2008 @ 5:46 pm

  29. I recently had my port 25 blocked. My wife and I are not spammers, and now we cannot use our Apple Mail to check our email. This recently happened to a friend of mine as well. It appears the blocks are random, as the Comcast Support explicitly told me there is no block on my port 25. I am in the process of contacting the local news to report this incident and make Comcast’s unjust policies known.

    Comment by Wayne I — 11/18/2008 @ 12:00 pm

  30. I just experienced this problem on all days, Thanksgiving.
    We couldn’t send any mail but could receive mail. Comcast is my internet provider but they are not who we go through for our e-mail. We have 2 domains through IX Webhosting and it’s their servers that our e-mails go through. I first contacted them and found out that they don’t block Port 25 but that they have this problem coming past there help desk everyday due to Comcast blocking this port. I then contacted Comcast and simply explained that 1) I wasn’t about to change anything on my end since it has been working perfectly fine for well over 10+ years and 2) I wanted to know why my modem (which belongs to Comcast due to us upgrading a year ago to the digital voice) was selected and Port 25 was all of a sudden blocked. They couldn’t of course tell me why they did this but they did unblock it.

    So, if you go through Comcast’s servers to get your e-mail then yes, Port 25 is blocked and you’ll have to set your out going to 587 but if you don’t go through Comcast’s servers for your e-mail and you use their modem, then this is were the block on Port 25 occurs. Call them and ask that the block on your modem be removed and more than likely it will be done in seconds. Problem with them doing all of this is that some of us (including myself) have no clue to what to say to get this problem rectified. The only why I found out was due to the help desk at our hosting company about the block but it was search on Google that talked about Comcast selecting certain modems and blocking Port 25 that way.

    Comment by Deborah — 11/28/2008 @ 6:55 am

  31. The comcast tech was an idiot. I tried asking them why this happened all a sudden, explaining I was concerned because that I read in a forum that maybe comcast detected an email worm that was sending out a bunch of mail via smtp and could this be why they suddenly started blocking?

    He proceeded to explain to me that’s impossible because comcast only supplies the internet mail servers, they don’t control outlook express, that’s not their product that’s a Microsoft product. WTF? That has nothing to do with it and I tried explaining that to no avail.

    I spent hours, like 4 hours, at my mom’s trying to figure this out. We both use comcast and I can still use port 25 fine so I first assumed it was a problem on her end so I didn’t call them up right away — first I disabled then tried uninstalled firewalls, virus scanner, using different email client… even tried port 587 per a forum suggestion. Turns out that I also needed to turn on smtp authentication to send email in addition to port 587.

    Comment by Pete — 12/1/2008 @ 5:17 pm

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