Unable to Send Email with Outlook Using Comcast

At Boxaid we see countless technical problems every day. Some are simple virus removal and some are complex technical problems that take several hours to diagnose and fix. We of course use Google religiously to look up additional info if we don’t know the answers off the top of our head.

We recently ran into an issue that was EXTREMELY difficult to diagnose. We saw countless articles that were also to diagnose the same issue but very little info on how to solve the problem. So we thought we would write a blog post in hopes of helping someone out.

Unable to Send Email with Microsoft Outlook

The issue was a user who was struggling to use Microsoft Outlook (version 2019 in this case) to send email via comcast.net and was getting intermittent errors connecting to the server for outbound email. Even worse, every time we connected to their PC we would send a test email and it worked almost every time. Once we disconnected they would send an email a few hours later and the outbound email would fail. Inbound emails were working just fine. This is a bit odd because most times email in both directions is often impacted. The message received upon delivery to Comcast Xfinity servers was something like:

[info_message style=”error”]”Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) smtp.comcast.net timed out. Try again.”[/info_message]

The message box we received in Outlook looks something like this

comcast xfinity email outbound fail


xfinity email outbound not working
Here is another example of the outbound email failure

What We Tried to Fix the Outbound Email Problem

We saw a few variations of this but generally it was some kind of encryption type error. We of course triple checked our mail server settings in Microsoft Outlook. You can find the official Xfinity settings for email on the Comcast website. Here are the instructions below in a nutshell.

When your program asks you to set up your email, use these settings to connect your Comcast email:

  • Incoming Mail Server Name: imap.comcast.net
  • Incoming Mail Server Port Number: 993 with SSL ON
    • If Needed: 143 with SSL ON
  • Outgoing Mail Server Name: smtp.comcast.net
  • Outgoing Mail Server Port Number: 587 (SMTP)
    • If Needed: 465 (SMTPS)
  • SSL Encryption: checked
  • Authentication: Type in your Comcast username and password

As mentioned we triple checked the settings above and tried several encryption options as the error message suggested but there was no luck. We tried deleting the entire mail file in Outlook and creating a brand new profile, also with no luck. We then tried monitoring the traffic and we noticed that Avast, the anti-virus product on the computer was monitoring the port in question.

Here is What the Solution Was

We personally installed Avast anti-virus (free version) which we use on our customer computers all the time with almost no issues. Until now of course. We took a closer look at the Avast settings and noticed that there were a few extra features installed focused around mail scanning.

avast mail shield settings

As shown above you have to click Settings, then Protection, then Core Shields. You then need to scroll down all the way to the bottom which makes its even harder to find these settings. Once you get there you will see that Avast is scanning outbound and inbound emails. We recommend completely disabling Mail Shield which instantly solved our problems around the outbound emails. Unfortunately, we have to blame this one on Avast. It seems the way they are trying to intercept the outbound email was affecting the encryption.

If you found this article helpful please leave us a quick comment below so we can see how many users this is affecting.

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