Can't Send Email



I recently got a new internet provider (att), and since then I am receiving
emails fine but am unable to send any via Outlook...I am getting this error
message...

The connection to the server has failed. Subject '', Account:
'mail.optonline.net', Server: 'mail.optonline.net', Protocol: SMTP, Port: 25,
Secure(SSL): No, Socket Error: 10060, Error Number: 0x800CCC0E

Any suggestions???

Liz
.