I have Zimbra desktop 2.0 on Windows 7 OS.
I have 6 accounts configured on this.
My problem is one of my POP Accounts have stopped syncing suddenly and when I edit the account settings and hit "Validate and Save" I get this error messege

Cannot connect to "SMTP server". Please check host/port and network connectivity.

Since my other accounts are working fine there should not be any issue of internet connectivity. Also I am able to use that POP account from the service provider's webmail access application.

Can anyone help me with this please.