I received the following message failure response:
Delivery to the following recipient failed permanently: email@example.com Technical details of permanent failure: Google tried to deliver your message, but it was rejected by the server for the recipient domain xxxxx.com by mailserver1.xxxxx.com. [xxx.xxx.xxx.xxx]. The error that the other server returned was: 550 Rule imposed as firstname.lastname@example.org is blacklisted on Spamhaus - see www.spamhaus.org
I went to the Spamhaus website and checked to see if my domain was listed on any blacklists, and it looks like we're not blacklisted at all.
We use Google Apps for our email, so I'm wondering if Google's IP address or domain was flagged as spam... or am I missing something? Thanks for your help.