Error with Comcast SMTP

I'm getting the following error when trying to send email via Comcast (SMTP)

Email+ Error Comcast Email: SMTP server connection error: [SSL: WRONG_VERSION_NUMBER] wrong version number (_ssl.c:1006)

My SMTP Server settings, as follows

smtp.comcast.net
SSL
Server port 587
Login: my email address
Password: xxxxxxx

Using the same login credentials for an IMAP server, it successfully logs in.

Any ideas on what I can do to get this working again? Email+ SMTP server was working a few weeks ago, now gives the error above and Indigo shows a State of "Failure".
The only Indigo change was an upgrade to 2023.2.0

What MacOS version is your Indigo system running?

Ventura 13.6.4

That error message usually means that there's an SSL mismatch. But we usually only see that with old versions of MacOS. Which would not be Ventura.

I read some posts that Comcast requires an option to be enabled in the web client for third party apps to work. But if this previously worked, you probably had that enabled, and I would think it would be a different error message in that case.

Try specifying port 465 instead of 587 and see if that helps.

Thanks, I'll give the port numbers some tests.

I did have the Xfinity checkbox checked (enabled) for the third party apps to work. When I started trouble shooting this problem, I checked on my Xfinity account, but found it was already enabled. The SMTP server had been working for a month or more without any problems. I had made no changes to my email account, and the only change made to the Mac Mini was the install of a security update a week or so ago, and the only change to Indigo was the upgrade to 2023.2.0 last week.

I can't be sure when the SMTP server stopped working, since I don't have Indigo sending email very often. Using Pushover most of the time for Notifications.

The fact that it works with IMAP and doesn't work with SMTP leads me to believe it's a difference in configuration of the different Comcast servers.

Mystery solved.

I wanted to put this one to rest. I'm embarrassed to say the problem was of my own doing.

After many try's with variations of the Encryption, Server Port, and checking and double checking the Login and Password, I had no success in making a successful SMTP connection.

Finally I decided I'd upgrade my Mac mini server from Ventura to Sonoma (planned on doing this anyway), but still no luck. Finally, I checked all the fields one more time and found my error in typing, which I had overlooked at least 25 previous times. In my Login name field, I had a "." instead of the "@" in the domain, which of course was causing an authentication error.

In my working career, I've always said have someone else proof your work, because it's difficult to catch your own mistakes, which is exactly what happened here.

So for Comcast, it worked with: SMTP host Name: smtp.comcast.net Encryption: SSL Server port: 465 and then my correct Login and Password.