AOL EMAIL stops processing passwords from 3rd party THUNDERBIRD client, using Windows 10 AND LINUX MINT versions 18.3 and 19. This is while using the provided access AOL settings from info page on 3rd party mail clients. Failure is all at once on all 3 different PCs.
Call AOL for help and the reply is to buy support services for a monthly fee, which will add up to an additional $60 per year over VERIZON's ISP services. I wonder how much extra money AOL made with this tactic. Looks like they try to force you to use e-mail via the AOL web site and the ( IMHO ) not too great interface. Guess it is easier for them to track you that way. Mail access via AOL website using the same e-mail address and password provided to THUNDERBIRD works all the time but lacks the ease of use and additional options offered by THUNDERBIRD. That access via browser also brings up a bunch of other stuff I don't want or need.
Apparently neither AOL nor VERIZON realize how critical e-mail access can be to many people.
I am not so invested in my VERIZON e-mail address that I wouldn't dump Verizon just to avoid AOL e-mail.
NOTE: I have used 3rd party e-mail clients for about the last 30 years and across OS/2, LINUX, BSD and several flavors of Windows without major problems of the type I have encountered since Verizon switched to AOL
to process e-mail.