Mail 5.3 will not send emails.

The problem

From my MacBook Pro Mail 5.3 will not send emails, using SMTP for my namesco account (for business). However i can receive emails for this account.

also my icould account works fine.

please note that for 2 years I have not had any problem until around December last year.

My attempts to fix the problem:-

I opened connection doctor and it had a red dot next to the smtp account with the following error

" Could not connect to this SMTP server. Check your network connection and that you entered the correct information in the Account preferences. Also verify that the server supports SSL. if it does not, deselect the "use SSL" checkbox in the Advanced tab Account Preferences.

I tried the account on my Iphone (with all the same details), and this worked fine. I could send and receive with no problems."

in terminal entered ping smtp.hosts.co.uk, and was receiving responses.

I tried to use the IP address instead.

I tried with SSL on/off

I reset a new password with namesco. (tried again on the Iphone and no problem but Mac book pro will not send)

in disk utility I ran the permissions verification program & repair the disk permissions

in disk utility i ran verity disk and repair disk.

in terminal i tried telnet smtp.hosts.co.uk, and received this:-

Any Ideas? as i am truly stuck cant figure out why my phone will sent emails but not my MacBook Pro.

Best regards,