Xtra.Co.NZ (Yahoo) Mail Receiving [SYS/TEMP] problem retrieving message. Error Code: -16999

I use Xtra.Co.NZ as my internet provider and they use Yahoo mail for their mail service.

Since they upgraded their systems and now use SSL protocol, I am receiving the following error message:

[SYS/TEMP] problem retrieving message

Account name:  "is my user account name"

Error code: -16999

I am on an iMAC 2010 Intel Core i5 running OS 10.9.2 (Mavericks).  My email client is Outlook for Mac 2011 which is current.

The service provided can't tell me what the problem is or fix it, nor can they reproduce it in their lab.

Apple tech support tells me to call Microsoft.

I either can't get through to them or get disconnected.

Can anyone help me resolve this?

Thanks.

Steve S.

New Zealand