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jbrooks · Aug 3, 2009, 12:40 PM

For the first time with my beloved Mac I'm at my wits end. All of a sudden a few weeks ago I could no longer send outbound emails through my ISP (Comcast) server. I've seen similar problems posted online but have not yet found a solution. Here is the background.

I use my comcast.net address as my main email address but also have a MobileMe acct with a me.com address. Up till a few weeks ago I could send and receive from either acct. I can still receive from both accounts but can only send from me.com. If I try to send to myself, the only configuration that works (i.e. registers in my In Box as having been received) is if I send FROM me.com TO me.com. If I send FROM me.com TO comcast.net it doesn't register in my In Box and of course no outbound comcast.net messages work. When I send from comcast.net the message shows as having been sent in my Sent box, and there is no error message that it has been bounced back. The comcast.net address WILL work for outbound email if I send from m internet webmail OR by using Entourage for mail instead of MacMail. Finally, a buddy of mine was able to get the MacMail acct to work with outbound comcast.net messages, and then it stopped working again. Same thing happened with an Apple tech support guy. So there seems to be some issue between MacMail and Comcast.

Here's what I've done so far.
Rebuilt my MacMail acct with Mac tech support.
Reinstalled Mac OSX 10.5.7 (this is my current version of Leopard)
Checked and rechecked my settings a billion times with Mac and Comcast tech support.

So to recap: On MacMail - comcast.net and me.com inbound both work; only me.com outbound works. On Entourage - both comcast and me work inbound and outbound.

PLEASE HELP!!!!!!!!!!

besson3c · Aug 3, 2009, 01:05 PM

Reinstalling OS X? Just for future reference, don't do stuff like that, this isn't a worthwhile troubleshooting step and obviously a very time consuming one. You can accomplish an even better and more revealing test by creating a new OS X account.

What is your SMTP server and port number?

jbrooks · Aug 3, 2009, 01:40 PM

My SMTP server is: smtp.comcast.net (for Comcast) and smtp.me.com (for MobileMe). The port is set at the default (25, 465, 587). I have tried every configuration of these port settings for comcast.net and none work. I have Mobile Me on the default settings and that works fine. So I think it must be some kind of port setting that I'm not aware of.

besson3c · Aug 3, 2009, 01:54 PM

Comcast probably blocks outbound access on port 25. I have no idea whether this guy's blog post is accurate, but he claims this as well: How to Fix Comcast SMTP Blocking Port 25 - Outgoing Email

Port 587 is reserved for SMTP submissions (it is called the "submission" port). Entourage probably just fails over to this port in the event that an auth to port 25 fails while OS X Mail probably doesn't. Try switching the port to 587. I'm assuming that OS X Mail is setup to authenticate to this server via "password"?

besson3c · Aug 3, 2009, 01:57 PM

Also, my advice: find an email provider that supports IMAP instead of POP. If you don't want to pay for one, GMail supports this.

CharlesS · Aug 3, 2009, 02:27 PM

Originally Posted by besson3c

Comcast probably blocks outbound access on port 25. I have no idea whether this guy's blog post is accurate, but he claims this as well: How to Fix Comcast SMTP Blocking Port 25 - Outgoing Email

Port 587 is reserved for SMTP submissions (it is called the "submission" port). Entourage probably just fails over to this port in the event that an auth to port 25 fails while OS X Mail probably doesn't. Try switching the port to 587. I'm assuming that OS X Mail is setup to authenticate to this server via "password"?

Dude, did you read his post? He's got the port set to the default, which tries ports 25, 465, and 587 and uses whichever one works.

jbrooks · Aug 3, 2009, 02:43 PM

I read the blog post you forwarded but it still doesn't answer my question. And yes I have tried each of the default ports - 25, 465, 587 - and none of them work. I really don't want to have to change my email service from MacMail but it's looking like that's my only choice which is insane. I also have a service ticket active with Comcast to see if they can figure it out. Isn't there another port setting to try??

besson3c · Aug 3, 2009, 03:06 PM

Originally Posted by CharlesS

Dude, did you read his post? He's got the port set to the default, which tries ports 25, 465, and 587 and uses whichever one works.

Sorry, I didn't have the UI in front of me at the time. I was envisioning radio buttons of each of those ports with default selected, which would be 25.

original poster: have you tried setting up Mail under a different OS X account? You haven't answered my question as to how you are authenticating to Comcast as well...

jbrooks · Aug 3, 2009, 03:43 PM

Sorry , I have SSL checked and use password authentication with my comcast username and password. I've tried with and without authentication. Neither works. Yes I have also set up a different OSX MacMail acct. Didn't work either. I think it must be some random port number that I don't know. On other posts with the same general problem they suggested different port numbers but they seem to be geographic specific. So a port number that works in NY apparently doesn't work in the Bay Area(?)

ghporter · Aug 3, 2009, 05:01 PM

This issue has been going on for how long? This could simply be a problem with Comcast's servers, or perhaps a "server change" that they didn't do a good job advertising. I've seen this a few times with other ISPs-they tell "everybody" they're changing servers as of some specific date, but they don't really get the message to everybody.

Have you made certain that you have your client configured correctly? Here are Comcast's instructions for setting up Mac Mail to work with their servers. I found it interesting that they have some very specific settings that aren't exactly "how everyone else does it," i.e. "password authentication" but not SSL, that sort of thing. I've run into this sort of thing myself and going EXACTLY by the ISP's instructions, however odd they may seem, is usually the best way to go.

Of course if you have everything exactly the way they want it and it still doesn't work, I would suggest calling their tech support. In such a situation it's definitely not you-you're getting some mail out-so that leaves them as the issue.

besson3c · Aug 3, 2009, 05:44 PM

jbrooks: if it works in another client like you said, there is no magic secret port number. If you are using Entourage v.X you will be authenticating via SSL on port 465, not TLS. OS X Mail doesn't support SSL connections (even though there is an SSL checkbox in the GUI it is actually TLS and not SSL). What port and settings were you using in your client that works?

jbrooks · Aug 3, 2009, 08:34 PM

I looked at the Comcast link and all settings are as indicated in the link. Looking at Entourage the settings are:

SSL checked
Port 25 selected
Requires authorization but specified that send settings are same as receive settings.

I have a ticket with Comcast but no news. Maybe they hope I'll go away?

Thorzdad · Aug 4, 2009, 07:16 AM

Comcast's recommended smtp settings are:
smtp.comcast.net
Port 587
SSL
Password Authentication

It's best to specifically set the port to 587. Comcast does block port 25, so don't use it. Optionally, you can specify port 465 (with SSL and Password authentication) Make sure you aren't using any other authentication type, especially MD5. Comcast does not support MD5.

jbrooks · Aug 4, 2009, 10:39 AM

I already did that. It didn't work

Big Mac · Aug 4, 2009, 10:59 AM

Do you have an Intel Mac or access to a Windows machine? If so, have you tried sending mail through it?

One time I remember my ISP making an internal configuration change that caused all Mac mail clients to fail while causing no problems for Windows clients. I wouldn't put it past Comcast to have done something that stupid, either. If you can test out your mail sending capability on Windows that would add to your knowledge of the problem.

Thorzdad · Aug 4, 2009, 11:13 AM

jbrooks...Have you gone onto Comcast's user boards and posted your problem in their Macintosh forum? People (including myself) seem to have much more success fixing an issue through feedback in the forums than they do with Comcast's tech support. There are a couple of very knowledgeable and helpful admins in the forums that seem to have a lot more on the ball than the tech support people do.

jbrooks · Aug 4, 2009, 12:28 PM

I have an Intel Mac. Don't think I have the Mac/Windows side by side feature and if I do I don't use the Windows side.