I'm at a loss, and I'm being bounced around by a ping pong by Comcast and Optimum. Let me state some facts. 1. The error I'm reporting here, I have NEVER EVER seen before.

And you are the second I know of to report it here in the last 24 hours.

2. I have 2 email comcast email addresses, they have worked with Thunderbird for over 15 years- no issues.

You have been exceedingly luck. That is not the usual experience. Especially with Comcast.

3. Optimum is my ISP for the past 5 yrs- no issues like this. I don't have an email address w/them. Seems they don't provide them anymore I was told by their rep!

Just a guess, and one I would have to have access to a comcast ISP login is that comcast will not allow access to their mail servers to get mail unless you log into the internet using their mail service. But it is a guess.

What the error message is saying is your IP address (that is your internet address allocated by your ISP and often messed with by a VPN resulting in similar issues to what you are experiencing.) is blacklisted from accessing the comcast server you are attempting to connect to. However I can not find that server named mentioned in the settings recommended by xfinity. https://www.xfinity.com/support/articles/email-client-programs-with-xfinity-email so perhaps all you need to do is update your connection settings in account settings and outgoing servers(smtp) to those recommended by the email provider.

Hi there- thanks for responding.

I don't know what you mean here

"Just a guess, and one I would have to have access to a comcast ISP login is that comcast will not allow access to their mail servers to get mail unless you log into the internet using their mail service. But it is a guess."

Their webmail accounts have a setting that allow their email to be obtained by 3rd party programs, such as Tbird.

I don't have a VPN. However, you could be right about updating my connection settings. I will have to call them.

Optimum was quick to say it's "comcast", until I squashed that and said- NO, when WiFi is on for my phone, NO email works, including Gmail. They didn't have clue on that one.

All they suggested is I exchange my router/cable box for a new one for a different IP address.

That didn't make too much sense as I asked them "isn't my IP address dynamic?" They said "some IPs are dynamic and some are not with the equipment"

Then I asked "can't you tell if my equipment has a dynamic IP or not, so I don't waste time for no reason..."

The problem with this error is when I look on the web there's billions of replies, and no one has the same situation. One guy had this AUTH error due to a Win10 update.

So there's no way to solve it for me at least. They don't know their own equipment, they disgust me.

The other part that is somehow connected is when my phone is not on WiFI, and I attempt to send an email from comcast #2 email address, my iphone mail app gives the error "Cannot Send Mail- The user name or password is incorrect"

And that simply isn't true. I've even typed it over again in the mail settings many times. These email errors are all connected somehow.

However, you could be right about updating my connection settings. I will have to call them.

Donty call them. Correct your settings using the information you have already been provided from their web site.

Optimum was quick to say it's "comcast", until I squashed that and said- NO, when WiFi is on for my phone, NO email works, including Gmail. They didn't have clue on that one.

I am just as quick to say it is not Thunderbird!

I have no idea why comcast as saying "[AUTH] Temporarily blacklisted IP Address - try again later" my guess is your provider is equally mystified as neither of us are the ones refusing to play. Comcast are!

My guess is you probably need to change your authentication method in account settings to oauth as that is now comcasts preferred method of authentication. Normal password has been replaced with oauth, which will take you through a series of web pages to authenticate and confirm your permissions for Thunderbird to access your mail.

viperc said

However, you could be right about updating my connection settings. I will have to call them.

Donty call them. Correct your settings using the information you have already been provided from their web site.

Optimum was quick to say it's "comcast", until I squashed that and said- NO, when WiFi is on for my phone, NO email works, including Gmail. They didn't have clue on that one.

I am just as quick to say it is not Thunderbird!

I have no idea why comcast as saying "[AUTH] Temporarily blacklisted IP Address - try again later" my guess is your provider is equally mystified as neither of us are the ones refusing to play. Comcast are!

My guess is you probably need to change your authentication method in account settings to oauth as that is now comcasts preferred method of authentication. Normal password has been replaced with oauth, which will take you through a series of web pages to authenticate and confirm your permissions for Thunderbird to access your mail.

Yeah no one there has a clue at my ISP. Called comcast, heard new message before TS came on. They have a problem with 3rd party mail clients due to some "issues". I've been elevated to level 2, prob with everyone else. The odd thing is you'd think my email would be affected equally, yet one comcast works fine. Today when I was trouble shooting with them. The problematic email address could not be verified by Apple Mail on my phone, then I tried it 2seconds later and it was verified, but it still only receives email, no sending.

I checked the settings, everything matches up to the website info.

I unplugged cable model and router for 5-10 mins, same Tbird issue.

Quick question- if I decide to create the problematic email address all over again in Tbird. If I remove the account, will I lose all my emails that have been downloaded, AND all my folders and saved emails?

I will not proceed until I learn that. I'm running the most current version of Tbird.

OR, can I create a duplicate w/out getting rid of the current emails addresses, like make them dormant...?