Email wont send......thunderbird, vista home basic

An error occurred sending mail: The mail server sent an incorrect greeting: 454 4. 7. 0 TLS not available due to local problem.

Sending of message failed.
The message could not be sent because the connection to SMTP server smtp. unifone.net.nz was lost in the middle of the transaction. Try again or contact your network administrator.

these are the messages i get when trying to send an email... ... ... ...

geek_cat1340, Aug 3, 5:42 pm

An unknown error has occurred. Subject '', Account: 'pop3. unifone.net.nz', Server: 'smtp. unifone.net.nz', Protocol: SMTP, Server Response: '421 454 4. 7. 0 TLS not available due to local problem', Port: 25, Secure(SSL): No, Server Error: 421, Error Number: 0x800CCC67

thats from windows mail account

geek_cat1340, Aug 3, 5:42 pm

these are the messages I get when I try to send emails from either thunderbird or windows mail, had the guy here today and they couldnt figure it out, it was all working fine then that started happening, they guy reckons there may be a firewall in place that is stopping it from sending, any ideas please? ? ?

geek_cat1340, Aug 3, 5:44 pm

ps I know its in another thread, but thought id start this on specifically for this problem thanks... ... . .

geek_cat1340, Aug 3, 5:47 pm