Kmail not sending due to socket failure

Hi there.
I am getting trouble when trying to send emails with attachments, I am getting the following error
"Sending failed:
Socket operation timed out
The message will stay in the ‘outbox’ folder until you either fix the problem (e.g. a broken address) or remove the message from the ‘outbox’ folder.
The following transport was used:
"

can anybody help me