This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Avatar for Username

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

This thread was archived. Please ask a new question if you need help.

I am getting this message when trying to log in: Sending of username did not succeed. Mail server mail.comcast.net responded: Plaintext authentication disallow

  • 2 replies
  • 1 has this problem
  • 87 views
  • Last reply by Pauldt

Pauldt
Pauldt
more options

I attempted to log in this morning and the system prompted me to enter my Comcast email account password. I am positive I am entering it in correctly. Then, this message pops up:

Sending of username did not succeed. Mail server mail.comcast.net responded: Plaintext authentication disallowed on non-secure (SSL/TLS) connections.

How do I resolve this?

I attempted to log in this morning and the system prompted me to enter my Comcast email account password. I am positive I am entering it in correctly. Then, this message pops up: Sending of username did not succeed. Mail server mail.comcast.net responded: Plaintext authentication disallowed on non-secure (SSL/TLS) connections. How do I resolve this?

Chosen solution

I contacted Comcast directly and found the solution. They recently changed their settings. To correct the problem, go to Thunderbird's Server Settings and change the Port from 110 to 995. Change the Security Settings on the Connection Security to SSL/TLS. Problem solved.

Read this answer in context 👍 1

All Replies (2)

Toad-Hall
Toad-Hall
  • Top 10 Contributor
more options

In Thunderbird

  • Help > Troubleshooting Information
  • click on 'copy text to clipboard' button
  • In this forum question, right click in a 'post a Reply' text box and select 'Paste'.
  • You can remove all info on fonts and printers, but do not edit anything else.
Pauldt
Pauldt Question owner
more options

Chosen Solution

I contacted Comcast directly and found the solution. They recently changed their settings. To correct the problem, go to Thunderbird's Server Settings and change the Port from 110 to 995. Change the Security Settings on the Connection Security to SSL/TLS. Problem solved.