email getting stuck in outbox

hi,
i am having problem in sending email. i have em client 5.01. when i send email, it gets stuck in the outbox and i get an error message bix. when i open it and go into diagnostics the smtp server needs to be fixed every time. can you please help.

Hello,

please download latest version of eM Client from here and write me back if problem persists.
http://www.emclient.com/dist/v5.0.183…

regards
Jan