I'm having an odd problem setting up Thuderbird to access my ISP e-mail account.

As far as I can tell all the ISP information is correct. I can recieve new e-mail but it won't let me send. Keep getting prompted for the password and even if I enter it is says it's wrong (which it isn't because I've checked and it's obviously working for downloading new messages).

My AV software/firewall (Kaspersky 2015) appears to be set to allow Thunderbird through so I'm at a loss as to what's causing the issue.

Any suggestions?

Windows 8.1 Pro 64bit, all up to date
Thunderbird 31 (whatever the current release is)

Two questions which I suspect would help with our investigations:

Which ISP are you using?

Are you trying to set up the account as POP or IMAP?

Doh.

Zen internet
POP

I've tried the destructions on the Zen website for setting up Thunderbird but they refer to version 3 I think so they're maybe a bit out of date.

even if you got a newer version it should still do it

in any case delete that pop email one

and set up a new pop one using your details

I don't have Thunderbird here, but two things to check.

1. Often you have to tell the mail client that SMTP needs the same authentication as POP3 settings.
2. Alternatively, some require that an SMTP attempt is preceded by a POP authentication, there is usually a check box for that.