I suspect this is a problem with the email tool you are using, not Firefox.

What website do you use to access your email? What happens if you try this in another browser, like Internet Explorer or Chrome?

I was using Chrome on my son's Mac in CA -- still the same problem as using Firefox on my PC here in NY.

I'm beginning to think it might just be AOL. Maybe it's time to say goodbye to them.

Thanks for that additional information. If you see the same issue in Chrome, the issue is almost certainly with the email provider.

I recommend you reach out to them or, as you say, try another provider. Sorry I could not be of more help.

Unfortunately, since I'm not a PAID AOL subscriber, my options with them are limited. But I believe they have a forum too, so I'll try that.

Thanks for your help, and I hope you have a nice weekend.

I went to the actual AOL site -- and the addresses did autocomplete. They must have done something to change it.

That's great! Glad to hear it.