SMTP error while sending mails in sugar 5.2.0e

[Gucons]

Hi ,
I was trying to send a mail to one of my lead and when i click send button iam getting the below error which i attached a screenshot. it is really diffficult to handle this when you have formatted the entire mail and it goes in vain. Sometimes it works perfectly fine.

I hope and request that someone will help me in this regard.
Waiting for your reply,

Thanks
Pavan

[newladder]

Hi Pavan,

I do get the same messages most often. Did you able to get this resolved. What was the solution?