Only if TMobile will be your email provider. To my knowledge, they do not do that, but I'm always willing to learn. :)

Thunderbird is ONLY an email app that connects to your Email Provider (example Yahoo, Gmail, Hotmail and many others ) and downloads email from your Email Provider to your device.

If you change your Internet Provider but DO NOT change your Email Provider then everything is ok.

Unless as David point out , if your Internet Provider is also your Email Provider then you will lose your Email address and all emails .

Yes, I understand and my old provider also provided the email. After some reading, I have now gone into Thunderbird and added my gmail account and will have to let many people and companies to change my old email I have used for 20 years! But, the good news is that I think I have Thunderbird running again. It is still a little funky in that it still comes up and says connection timed out and wants a password but when I don't give it a password and just click on OK----it seems to be downloading the emails and letting me use the program?

If you are not able to keep email address then...in Thunderbird, I suggest you get copies of all emails from that account and put them into a suitably named folder(s) in 'Local Folders' account OR if still using old provider you could access webmail account and get them all forwarded to your gmail account.

Once you have copies in Local Folders account and they all look good - you can read emails, then you can remove the old email address account via 'Account Settings'. Finally, access Settings > Privacy & Security > Saved Passwords and remove all lines for the old email address/account.

re :wants a password but when I don't give it a password and just click on OK-

What password ? Does it ask for Primary Password ? Did you ever set up a 'Master Password' which is now called 'Primary Password' ? Do not confuse this with a mail account password. Primary Passwords which should be a unique password only you know about, it's usually set up because you share your computer with others and also allow them access to your User Account. It's designed to stop prying eyes seeing stored passwords even if they can see mail accounts/emails etc. If yes, then it will ask for it once per session. Note: It will also ask for it if you want to see any 'Saved Passwords' otherwise it ask for the User Account password - the one you enter when starting computer to get access to User Account.

Info on Primary Passwords: https://support.mozilla.org/en-US/kb/protect-your-thunderbird-passwords-primary-password

If you are not able to keep email address then...in Thunderbird, I suggest you get copies of all emails from that account and put them into a suitably named folder(s) in 'Local Folders' account OR if still using old provider you could access webmail account and get them all forwarded to your gmail account. Once you have copies in Local Folders account and they all look good - you can read emails, then you can remove the old email address account via 'Account Settings'. Finally, access Settings > Privacy & Security > Saved Passwords and remove all lines for the old email address/account. re :wants a password but when I don't give it a password and just click on OK- What password ? Does it ask for Primary Password ? Did you ever set up a 'Master Password' which is now called 'Primary Password' ? Do not confuse this with a mail account password. Primary Passwords which should be a unique password only you know about, it's usually set up because you share your computer with others and also allow them access to your User Account. It's designed to stop prying eyes seeing stored passwords even if they can see mail accounts/emails etc. If yes, then it will ask for it once per session. Note: It will also ask for it if you want to see any 'Saved Passwords' otherwise it ask for the User Account password - the one you enter when starting computer to get access to User Account. Info on Primary Passwords: https://support.mozilla.org/en-US/kb/protect-your-thunderbird-passwords-primary-password

My Thunderbird, when it first comes up, says "Login to server imap.iowtelecom.net with user name jmillsp failed. Then gives me the options to RETRY, ENTER NEW PASSWORD or CANCEL. Soooo, if I click on Retry or Cancel or even enter a new password, I have tried all three----it still comes up but, so far, if I click on any of those, I am still able to use Thunderbird. The iowatelecom.net is the email address I will be losing, I think, we I notify them that I want to disconnect there service since I now have a faster and more reliable one through wifi and not a DSL. The other issue that it says is "Connection to server imap.windstream.net timed out." But, for whatever reason, I am now able to use Thunderbird even with those nuances.

re :The iowatelecom.net is the email address I will be losing,

That is an imap mail account. All imap folders synchronise with server. That means all emails are stored on server. If imap account manages to connect to an empty server then all emails will be lost. If you want any of those emails in that account then you must get copies of emails into Local Folders.

re: "Login to server imap.iowtelecom.net with user name jmillsp failed.

The username should be the full email address not just the bit before the @. Maybe you need to make sure you have correct username. Check in Account Settings > Server Settings for the account.

iowatelecom.net is owned by windstream, so both of those email addresses are provided by same provider.

re :The iowatelecom.net is the email address I will be losing, That is an imap mail account. All imap folders synchronise with server. That means all emails are stored on server. If imap account manages to connect to an empty server then all emails will be lost. If you want any of those emails in that account then you must get copies of emails into Local Folders. re: "Login to server imap.iowtelecom.net with user name jmillsp failed. The username should be the full email address not just the bit before the @. Maybe you need to make sure you have correct username. Check in Account Settings > Server Settings for the account. iowatelecom.net is owned by windstream, so both of those email addresses are provided by same provider.

So, wondering if I should delete the iowatelecom.net from Thunderbird since I am closing the account with Windstream or does it really matter? I have linked gmail to the account.