Can not validate

[AussieThai]

Zimbra desktop has been working well for several months, however for about the past week, every time I try to Validate, I receive the following message -

"zimbra.imap.mail.yahoo.com:993" host not found. Please check hostname and network connectivity

Any ideas on how to resolve this problem woulkd be much appreciated

[phoenix]

Check if you can get to it from the command line with:

telnet zimbra.imap.mail.yahoo.com 993