next time you might edit the account settings in

Tools menu (ALT+T) > Account settings > server settings. 

The mobile server selection was a very deliberate one. Use their recommendation on a laptop and try and send mail from a hot spot. Nada. You must connect to the Internet using Charter for their recommended server to work. A very lackluster solution that is a hangover from dial-up days. The Mobile server however works regardless of how you connect.

You have gone a very long way around to fact that Charter have been obviously reported for sending SPAM and their mail server blacklisted. When will Charter have their server back in service? All mobile devices, phones, laptops tablets use it so it is very important to many of their customers. My experience with blacklisting is that 24-48 hours are required to get all services to remove their entries. But I am a one man band, they are a major corporation. They might get preferential treatment.

That menu doesn't allow me to ENTER an Outgoing server setting, just select from the ones already present.

For me, at least, this laptop doesn't often go anywhere, and I have alternate email accounts to use when I'm not on Charter's network.

I spent >90 minutes with Charter support and when I said I could send email from their web site they refused to escalate the issue. Ostriches!

Tools menu (ALT+T) > Account settings > outgoing server (SMTP) then.

That menu doesn't allow me to ENTER an Outgoing server setting, just select from the ones already present. So I have to create a new (perhaps dummy) account in order to insert it into the list. I'd expect it to allow an entry to be typed in but it doesn't. T-bird 24.3.0 for Windows 7 64-bit I solved it by doing just that.

Well I have an add button just above the edit button, don't you?

Changing the ports was simple enough to do but my inbox times out. Now I have an inbox and outbox that times out.

Would changing both imap and smtp to mobile do any good?

I was able to receive emails with mobile for my imap. Since system recovery, and a malfunctioning backup drive, I haven't been able to send anything out of Thunderbird. It usually times out. And Web mail is a pain.

I'm not completely clear on some of these suggestions. I'm just too thick headed after a month of having one computer problem after another to do anything but clear instructions and explanations.

Sorry, ever so much. After almost 40 yrs of computers, I've just about had it with them, but, to paraphrase Dell's old ad. "I need the computer for day to day maintenance of my insanity."

just ditch anti virus scanning or your email njnagler. If you want to go further, open your own support topic. This one has been idle for months and should be left that way really. I am pretty sure martin82 does not need your support request emailed to them as is happening.