Hello

I am suddenly having a problem sending or receiving mail to yahoo adresses. I am guessing they changed something in their configuration that causes my sending domain not to be recognized. Now when I send mail I get errors like:

No MX or A records for blahblah.com

or

Domain of sender address jk@blahblah.com does not resolve

----
I do have an MX entry in the DNS record:

$TTL 86400


@ IN SOA www.blahblah.com. root.www.blahblah.com. (
2003070701 ; Serial
28800 ; Refresh
14400 ; Retry
3600000 ; Expire
86400 ) ; Minimum
;
; Name Servers
;
IN NS www.blahblah.com.

;
; Mail Exchangers
;
blahblah.com. IN MX 0 www.blahblah.com.


Can someone please tell me why I might be getting these errors?

Thanks!