You’re not alone…
Users all over the country are finding out daily that suddenly, for no apparent reason at all, they are unable to send mail if they want people to reply to their business or personal e-mail addressed other than one that is @comcast.net. This is because Comcast is blocking port 25 , which is your default port for sending email through your mail software.
The error message says (fill in your own X):
The connection to the server has failed. Account: ‘XXXX’, Server: ‘xxx.xxx.xxx.xx’, Protocol: SMTP, Port: 25, Secure(SSL): No, Socket Error: 10060, Error Number: 0×800CCC0E
Gee that’s helpful, isn’t it?
If you are using mail.yourdomain.com for your SMTP outgoing mail server, then you get an error saying “unable to connect to the mail server” even though it just successfully connected to the mail server to retrieve your incoming mail. After wasting time calling your web host, and going through various troubleshooting techniques, they tell you to call Comcast.
To make matters worse, users are finding out one at a time, because Comcast is slowly rolling out these changes user by user in individual markets around the country. This month, it’s apparently Portland Oregon’s turn, where I live.
To cut to the chase, here’s the solution:
Change the port your computer is using for SMTP outgoing mail, from Port 25 to one that your hosting provider will allow. In most cases, this seems to be port 587 for Portland providers.

To do this in Outlook -
- Go to tools – e-mail accounts – view or change existing account
- Sselect the appropriate mail account and hit the change button
- Go to the more settings button, and into the Advanced tab
- Change your default port 25, to port 587, and you should be back in business in most cases.
Still broken?
- Added note from comments below – Some people in the midwest for whom 487 didn’t work succesfully chaged to 465 and picked SSL under the “use the following type of encrypted connection” drop down. They did not check the “this server requires an encrypted connection” box.
In Outlook express -
- Go to tools – accounts – Mail tab
- Choose Properties box – Advanced Tab – and from there you can do the same
The reason Comcast claims to be doing this is in an effort to prevent spam being sent by zombie/spyware/virus laden computers using their bandwidth and their Internet connection.
I suspect they are really doing it to limit liability for any future potential lawsuits, and not really to save bandwidth, but I have no problem with that.
The problem with Comcast doing this is that they do not seem to be telling all of their support people, and do not be notifying their customers. This has been going on around the country for MONTHS.
Instead, it takes the end user hours of frustrating time on the phone spent with lower-level tech-support who have no idea that this change has even taken place.
One can only guess how many individual users are still frustrated at this very moment because they are being forced to do their business e-mail from home using their @comcast.net accounts, after uninformed Comcast agents are able to help them?
As a web host, we were forced to spend hours dealing with Comcast before we got an actual answer, and we still lost a couple of hosting customers over it, who were convinced that it must be our fault, since Comcast told them it was.
Great customer service. If there was any competing product in my market I would switch in a heartbeat. I tried once before in 2005 after nearly an entire summer of poor Comcast connectivity.
Thanks Comcast, for valuing our time so very little, in your quest to make mega millions.













Matt Sands says:
Outlook 2007 has an autoconfigure function, which asks you to put in your email address and password and proceeds to search for the correct settings. When I tried this, it not only used 587 for outgoing, it changed my incoming to 997, required an encrypted connection (SSL), required logon using secure password authentication, and used TLS type of encryption. Servers are mail.comcast.net for incoming and smtp.comcast.net for outgoing, so no change there. Perhaps these settings will help some people.
Rob Bursmith says:
Thanks, they’ve been slowly disabling ports first 25, then 587 with authentication now, 2525. I’m getting pretty fed up truth be told.
Alix Saint-Franc says:
Ladies and Gentlemen,
I am in the Northern Virginia are. Does anyone know which port should I use for comcast smtp for the outgoing mail for this region?
Thank you in advance for your help.
Sincerely,
Alix
drpagal says:
put 1025 for outgoing SMTP. this is what comcast told me and it works
drpagal says:
I am in southern MD, so 1025 should also work for you
drpagal says:
try using smtp port 1025, i am in southern md and it works for me
Jane Carter says:
Give 587 a try, just might work.
But do give them a call, because you just might get someone who knows something.
I was lucky. Though I dont understand why they dont let their customers know what to do.
I should sell my Comcast stock, as they seem to not be doing that well,,,,,,,,,
Anyway, give 587 at whirl,
Jane
TDK says:
Got the Comast note – made the changes to 587 for outgoing port. Now, as far as we can tell everyone is getting our e-mails EXCEPT anyone on Verizon.net. That’s right – we can send and receive to/from all our contacts via Outlook Express 6, BUT to our contacts who use Verizon, they do not receive any mail from us.
Any thoughts? Of course Comcast says it’s Verizon’s fault, Verizon says they are not receiving the mail to their servers.
Bill says:
TDK,
did you ever find a solution/get your issue with not being able to send emails to Verizon customers resolved?
I’m having the exact same problem right now.
Thanks,
Bill
bselling@comcast.net
Brigitte says:
I was able to at least figure out the problem if you are using Outlook and a solution, but not a great solution. It seems that using Outlook with Comcast looks like spam to Verizon. Verizon customers’ default configuration blocks the spam. If the individual user goes to Mail Settings –Blocking- Safe List and adds “Comcast.net” it will work, but there has to be a better solution. If you have one please let me know.
TDK says:
p.s. We are in the Baltimore area.
MM says:
I am in the NW suburbs of Chicago and nothing above worked except SSL on port 465. Not even port 1025 worked. How frustrating, because when I log into any other ISP or use my Verizon wireless USB card the normal port 25 works great the first time. What a crock that Comcast does this.
Angela says:
I am located far west of the western suburbs of Chicago and began having the same problem – just started last night.
I tried all of the recommended ports until I saw your post and YEA ! It worked.
So any Chicago / Suburban users might want to try the settings you gave – SSL on port 465.
Thanks so much.
I feel sorry for all those users who don’t understand the whole port thing and will be wasting gobs of time trying to get it corrected.
Shameful of Comcast to put people through this.
SB says:
In the Denver area, try port 3535. This works 50% of the time for me. Annoying as hell, but at least it SOMETIMES works.
IBG says:
I’ve tried most of this…and can receive email from Yahoo, but can’t send to Yahoo. Annoyingly enough, I can send to Yahoo from my Blackberry (same Comcast Account). Any thoughts?
Scott says:
sorry, but “Can’t send to Yahoo” doesn’t exactly give us many details.
Although it sounds unrelated to the port blocking issue subject of this post, please share the details of your error messages or bouncebacks and someone can likely seteer you in the right direction.
Bozena says:
Does anyone know which port should I use for Comcast IP in Chicago for going and coming in mail. What settings should I use for Outlook 2003. I have tried every possible info, called Comcast they do not know S..or they just don’t want you to know but my Outlook mail is not working
Thanks
Scott says:
Call the host of your domain – Perhaps you’re not the first Comcast user they’ve had the issue with?
John says:
Initially, I changed the SMTP port while not changing any of my other settings. It didn’t work but the error message mentioned something about authentication, so I went back into the settings and enabled the option to signify that my outgoing mail requires individual authentication and I selected the option that my log on information is the same as it is for my incoming mail. I tried again and it worked. I am able to receive incoming email.
Sal says:
Thank you SOOO much for this post. It had helped me a lot. I am using Domino server to send and receive e-mail with my own domain. Right around Christmas, I noticed I was not able to receive or send e-mail. I finally figured out how to send an e-mail (port 587) but still having problem receiving e-mail. Can anyone please help me with that. Called comcast so many times but NO help. They couldn’t even tell me which port are they using for SMTP inbound (listening port). If you ask them, they tell you 110 which is for pop3. ANy help will be greatly appreciated.
Jason says:
I can see a nice little class action law suit here.
We pay Comcast for internet service, it’s well known that ports 25, 80 and 110 are the most commonly used and “needed” ports to browse the internet. And they block port 25? I don’t think so, we’re not getting what we pay for!
Julie says:
I have chnaged outgoing server to port 587 as requested. but still – anyone with a verizon.net account doesnt receive my emails and of course I’m never notified that they dont go thru..I’m in MA area- any suggestions?
Brigitte says:
? I was able to at least figure out the problem if you are using Outlook and a solution, but not a great solution. It seems that using Outlook with Comcast looks like spam to Verizon. Verizon customers’ default configuration blocks the spam. If the individual user goes to Mail Settings –Blocking- Safe List and adds “Comcast.net” it will work, but there has to be a better solution. If you have one please let me know.
Bill says:
very helpful article.
Steve says:
Today is Friday Jan 22. My first exposure to any of this was Mon Jan 18 when I suddenly could not send out anything. I started calling Comcast Monday evening. They offered the 587 fix and it didn’t work, which only managed to block my incoming mail,and suggested it was my other email provider which is RCN. Called RCN who put the burden back on Comcast. Then I thought, maybe it was a Microsoft problem with Outlook. After checking with MS sites and posting messages, I started looking up port 25 and 587 since that is what Comcast was working with. Discovered this Port 25 issue regarding spamming and saw that it went back more than a year. Went back to Comcast and talked with 2 more techs (including one in the Phillipines). All 3 said the same … if 587 doesn’t work then we can’t help you, those are the only options.
Acquired more information and was more irate. Wrote back to Comcast who suggested to call customer service. I wrote back and refused, I wanted all this in writing and expressed a lot of anger. Lo and behold, a full explanation about spamming, the possibility of a virus and another port suggestion … 465, which also included referring to my comcast email address which I never used. Hmmm, so I re-established that and that combination finally worked. (That was Wednesday). It took a lot of ranting and raving to get a solution, which was so simple and basic. My concern was that my outgoing mail would reflect my comcast address, but it didn’t. My other domain address still showed.
Scott says:
Thanks Steve, you are the second person to report that port 465 and “verify outgoing” with your comcast email address / password works. Amazing that they can’t Share this with most of the comcast support.
Steve says:
Just a follow-up to that. When everything started working again, I wrote a thanks to the rep but STILL blasted Comcast. 2 days since then and I haven’t gotten an acknowledgement. What a surprise. This what I wrote:
“I am still very angry at the incompetence of the technical assistance, which as it turned out was very basic changes, to which they had no clue, including a re-direct to customer service in the Philipines. Evidently this port 25 issue and, it seems, by my experience 587, has been going on for some time … more than a year and I found several techincal websites of many angry comcast customers who were treated just as poorly with no forewarning of service interruption or an explanation of what triggered their outgoing blockages. I am telling you this right now. This NEEDS to be addressed to the entire Comcast community and a letter of explanation in the next billing and is the least that should be done. Like me, not everyone exclusively uses comcast email, but rather another domain through your server and they are going to be just as angry and frustrated by the lack of resolution they will try to get. It’s terrible that I had to rant and rave to get this accomplished.”
On deaf ears, probably :-0
donn in CT says:
I have tried all of the port changes with no luck. I am in central CT and began experiencing the “no send” problem a week and a half ago. Comcast was no help. Can anyone suggest a viable STMP port for my part of the country?
Steve says:
Hi Donn,
I could only give you the specifics of what I use and what I did using Outlook Express 6. Don’t know what you are using. JUST changing the number wasn’t enough.
In any case the outgoing port number, again, was 465, noted under the advanced tab. On the servers tab… Outgoing mail checks “My server requires authentication”. Clicking the settings tab next to that, brings up the logon info screen with the option to logon using …. and that is where I put my comcast user name and password. “Remember password” is checked.. “logon using secure password authentication” is not checked.
That’s all I did and everything worked after that.
Stephen says:
I am using Outlook (NOT Express). Today was the first time I had sending errors from Comcast. I called their support and was told they could not help me. I have tried all of the FIX numbers suggested on this site and none have worked. I live in the midwest. Has anyone been able to solve the number quest?
Adalberto Quintana says:
Well, outgoing SMTP server should be set to port 1025 and it’s work fine with comcast e-mail, it’s explain very clearly here in this blog.
Thanks for this valuable notification.
Miguel says:
All,
I live in Indianapolis and am experienced the same issues with Comcast. I had everything running through my Exchange Server using port 25 and smtp.comcast.net as my relay. Every e-mail passed through until today when suddenly all outbound e-mails got stuck in my queue. I have tried the various ports listed above in the suggestions but they have been unsuccessful. Curses Comcast!
Miguel says:
correction “am experiencing the same issues”
Scott says:
Any resolution yet for you, @miguel? Have you phoned Comcast?
Miguel says:
Scott,
I bypassed going through Comcast as it might not get me anywhere. I got an e-mail account through my domain registrar and bought a SMTP relay to “workaround” the blocked port issue.
RH says:
I’m now getting this in the South Bay Area/Silicon Valley. My port was already set to 587. In the settings options in Outlook 2010 Beta, when I click the Test Settings button it ok’s both out going and incoming mail, but will not send out going mail. The error message is the server timed out… Just wait or is this a port number issue? Thanks.
Richard says:
I have Comcast and I assure you that all emails going to anywhere other than verizon.net go through. I have just file a complaint against Verizon and you should too at :
https://esupport.fcc.gov/sform2000/formB!input.action?form_page=2000B
I can receive emails from Verizon, I can send emails to Verizon only through SmartZone.
Scott says:
I believe this is unrelated to the port 25 change, but yes, I’ve seen this before – not a bad idea to get your voice heard – thanks for leaving the link for others…
chris says:
i, too, was suddenly blocked for outgoing mail on 2/9/20 at 3:29am–am in detroit area. comcast tech assured me i was NOT blocked, but…changed to port 587 out & 995 in. fine. still interested in why this happened, though, and found comments/blogs going back to ‘07. if interested, check out this link: http://www.comcast.net/terms/network/
don’t know why it won’t highlight, but, anyway…very enlightening.