"Thunderbird failed to to find the settings for your email account; "

Usually that error message relates to accounts on small providers or folks that have issues either with their DNS (unlikely) or and anti virus firewall that has gone out of control.

Given Comcast is listed in the setting as a provider https://autoconfig.thunderbird.net/v1.1/comcast.net the problem is your firewall blocking Thunderbird from accessing the internet.

Thunderbird has just updated to version 60 which exacerbates the number of reports we see here, and makes my replies more and more terse as the problem is with the anti virus, not Thunderbird. After years of reports from folks with issues, particularly the customers supplied the product by their Internet service provider my tolerance is not what it was, or should be.

If you have Norton's products you will have connectivity issues after an update because their product is fundamentally flawed in the way it does it's business. Sometime re installing Thunderbird will jar the rubbish product into accepting access to the internet. Sometime fiddling with the firewall settings for Thunderbird will fix the problem. The guaranteed fix is uninstall the product.

Matt, your observation that my problem is usually due to either DNS issues or antivirus firewall was helpful in tracking a workaround that has temporarily fixed my problem. First, I'm not running a firewall in Linux Mint 19 though I could nor do I have any Norton products. This led me to focus on DNS issues. After a search for forum posters with a similar Comcast problem, I found that Toad-Hill, while helping a poster, had identified the problem as name resolution for imap.comcast.net. His workaround was to reset the server name to imap.ge.xfinity.com (the canonical name for imap.comcast.net) and to submit the account password for the newly named server. I tried it with my password and it worked beautifully after overriding a complaint dialog that said this action may not be safe. Thunderbird then downloaded from the server over 20,000 older emails I was saving plus new unread ones and all was happy. Thank you and all the other volunteers for the work you do. It is appreciated very much.

Within Thunderbird, navigate to Preferences/Advanced/General. Select tab 'Config Editor...' then Search IPv6 and change network.dns.disableIPv6 value to True.

LinuxMint OS

Tech_1 said

Within Thunderbird, navigate to Preferences/Advanced/General. Select tab 'Config Editor...' then Search IPv6 and change network.dns.disableIPv6 value to True. LinuxMint OS

Is this just a guess, or do you have information indicating Verizon has IP V6 issues. I know they did some years ago, but I understood thy had sorted them out.

only fix that worked for both POP and IMAP installs on my linux systems. changing server to imap.ge.xfinity.com failed. managed to get imap+ in Evolution email client to digest imap.ge.xfinity.com after accepting 'bad' certificate. seems imap.email.comcast.net works with a valid certificate.

solved my issue with Comcast email within Linux Mint installations when days of searching other solutions failed. not sure of issues with Verizon.

it's been suggested the DNS issue lies within systemd of Ubuntu.

so not a guess, just worked for me.

Tech_1 said

so not a guess, just worked for me.

Thanks for the additional information. It is exactly what I was looking for. It is something I have not looked at for years, but might be an issue in several threads I have been participating in here. I will have to look further.

I found the file but I am not sure how to change the value. I clicked on it but I can only highlite the row not the column.

DaveDave said

I found the file but I am not sure how to change the value. I clicked on it but I can only highlite the row not the column.

Right click gets you a menu.