Bid invitations are not going to Vendors

Hi,

We create BId invitations, but vendors are not recieving these invitations. We created contact persons and maintained vendor email address and everthing is working fine till last week. we got compalin that not recieving any Bid Invitation emails this week.

When we see T-code SOST, all vendor email address are showing in Greena and saying everything went fine...can some one tell me where could be the problem...and where to check.

If it didn't go to one vendor i can understand there is problem from vendor side...none of the vendors getting BId Invitation emails...

Thanks,

Ravi