re :One of my accounts suddenly stopped receiving emails from anybody.

Is this a pop or imap mail account? Please logon to webmail account via a browser. If you use 'Pop': Q: Do you see new emails that have not downloaded to pop account in the webmail Inbox? please also check the webmail 'Spam' folder for new emails because pop accounts cannot download anything that gets auto put into the server 'Spam' folder. You would need to move them into the webmail 'Inbox' folder.

If this is a gmail account, please check the 'All Mail' folder to see if you old previously deleted emails still in the 'All Mail' folder. If yes, then delete them.

If there are no new emails arriving on server, then obviously Thunderbird cannot download something that does not exist. It could be that you have reached your quota and the server cannot accept any new mail until you have deleted some emails off the server. If pop account: delete old emails and check to see if you have emails you thought had been deleted but still exist on server. Empty the webmail 'spam' and 'trash' folders.

If imap account: Q: Do you see new emails that have not downloaded to imap account in the webmail Inbox? Do not delete any emails in webmail at this point because you will also lose them from the imap account. If this is a gmail account, please check the 'All Mail' folder to see if you old previously deleted emails still in the 'All Mail' folder. Note: if you have not been putting deleted emails into the gmail imap trash folder, then those emails may only have had the label deleted and so could still be lurking in the 'All Mail' folder. Only delete 'All Mail' folder emails that you know have previously been deleted in/via Thunderbird

In Thunderbird See if you have reached a quota limit. Right click on 'Inbox' folder and select 'Properties' Click on the tab called 'quota' What does it say ?

Toad-Hall...

Thanx for the prompt reply.. I'll answer your questions as best I can (I'm a bit of a novice w/ all this).

I's a pop mail account. Oh, and not only not get incoming emails but can't send either. Brief me on how to log onto webmail account, Did it when we set it up years ago, but lost the how of it now. When I get on to the server, I intend to delete all old stuff in all the folders. (with pop once it's downloaded to my imac, its of no use anymore. correct?)

'Nother point. The error msg with the failure to send seems to say that it can't get to the server because it doesn't recognize the password.

Jim

re :I's a pop mail account.

This means all your downloaded emails are downloaded and stored on your computer. Pop account folders do not synchronise with server folders.

re: Deleting emails off the server: If the pop mail account has settings to download full copies and not 'headers only', then you will have full copies downloaded and so you could delete unwanted emails off server via webmail. But it may be worth keeping the last month worth of emails in Inbox just in case you need to download again - but if you backup your profile you will have your own backup.

How to access webmail account: This is done via a browser eg: Firefox, Internet Explorer, Chrome, MS Edge.

You logon using your full email address and password for that email address. Servers all have their own internet logon page. If you do not know it, you can use the search in a browser. If gmail account try typing: gmail logon Gmail Info which also includes a link. https://support.google.com/mail/answer/8494?co=GENIE.Platform%3DDesktop&hl=en

If you use BT, then type: BT logon Browser Search would produce a link like this: https://home.bt.com/login/loginform

If VirginMedia type: Virginmedia logon You will get results / links that say 'sign in to my Virgin media'

These are just examples, but I'm sure you get the idea.