Does https://support.mozilla.org/en-US/kb/cannot-receive-messages help?

Thank you, Wayne. Since my original post, I located the Activity Manager, and it shows what appears to be what I would describe as a "lock up" (don't know exactly what to call it). It shows a line for "Indexing messages". The green "thermometer" bar is all the way to the right, and underneath it says "indexing 201 of 407 messages in Sent (49% complete)". It seems to be stuck there. There is other stuff below that related to my AOL account, but the tasks seem to be completed. The Thunderbird app on my laptop is having the same email issue and shows a similar message. When I was reading through some of the online solutions yesterday, I recall something about an email "clogging" up the system. I will check the other settings as suggested in the link you provided, but before I go changing something and screwing things up more, is there anything to this "indexing messages" situation and might it be related?

Wayne - I checked the server settings, and the server name had to be changed. I looked up the server name online, put it in, restarted, and the emails downloaded as usual. Thanks!

Hey Harry! I'm having the exact same issue with Optimum Online. And it started for ME on September 9th. What did you change your server name to? I've changed to mail.optimum.net, restarted and still not working.

Can you post your other server settings please? I'm stuck! Thanks in advance!

PS I can add that I'm on a Mac and am currently using Mac Mail in IMAP mode and it's able to send and receive my Optimum Mail just fine.

UPDATE!: Apparently solved! I randomly changed the Server Setting Connection Security Setting from "None" to "SSL/TLS". And hit "Get Messages" and it downloaded all the messages since 9/9! Crazy. . Optimum must have changed something on their end. . fricken nighmare. Anyway, I'm still in "Troubleshoot Mode" so we'll see if when I restart with all my add-ons activated, etc. if it still works. If not, I'll update, otherwise I think it's SOLVED!

UPDATE: Had to change OUTGOING server to SSL/TLS as well or it wouldn't send email.

Hi Jumpeeman,

I changed the POP mail server to mail.optimum.net and kept the port setting at 110. This resolved my problem, and the emails started downloading on my PC. I didn't have to change anything else and never went into "Trouble Shoot" mode.

Sounds like you fixed your problem, too. Hope everything worked OK after your restart!