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

I don't understand what you mean with 'email is still coming through on the Network Solutions account'.

Isn't that the very same account you set up in Thunderbird?

I wasn't getting my mail - but I deleted the account and set it up as a POP3 instead and the email is coming through to Thunderbird but I can't send outbound. Also, I'm not sure how that will affect synchronizing with my iPhone. Can you send me an article link on how to set that up? Thanks

I deleted the account and set it up as a POP3 instead

Instead of what?

I can't send outbound.

https://support.mozilla.org/en-US/kb/cannot-send-messages

how that will affect synchronizing with my iPhone.

What's your account type on the iPhone?

Instead of IMAP

I don't have it set up on my phone yet.

I went through all the instructions and still cannot send email. I am receiving email. It says: The message could not be sent using SMTP server smtp.allenpaper.net for an unknown reason. Please verify that your SMTP server settings are correct and try again, or contact your network administrator.

I looked at the server settings and according to your instructions and those from Network Solutions, everything is ok.

Any other suggestions?

Ok, I changed something and the email is sending now.

Since I have this set up as a POP3 account, does that mean my messages are stored locally on this computer and cannot be accessed from another location or device?

Thanks!

That's basically correct. You can tell Thunderbird to leave messages on the server though, so that other devices (e.g. like your phone) can fetch them. But compared to IMAP this is a crap solution IMV.

Any way to fix it to IMAP?

just in case, can you send link to instructions for telling thunderbird to leave my messages on the server?

Thanks.

You can set up the account as IMAP in parallel to the existing POP account, assuming your email provider offers IMAP. http://kb.mozillazine.org/Convert_a_POP_account_to_a_IMAP_account

Wrt 'Leave messages on the server' see http://www.gn.apc.org/support/how-setup-thunderbird-leave-messages-server

When I try to set up the IMAP account, it tells me my user name or password is incorrect, although Thunderbird seems to automatically detect the server settings.

Here is the first step, does your provider offer IMAP email service? If no, end of discussion.