Cannot send email in or out using Horde

[fedel]

Hi, i seem to be having a problem sending email from horde:Iam getting the following error :
There was an error sending your message: unable to connect to smtp server localhost:25

The plesk setup is a failry new 7.5.4 and ive browsed through the forums and i cant make heads or tales of what to do.
Absolutley appreciate youre assistance.