Earlier today, er experienced a problem with email delivery from server WWW-29 (Dallas) to Gmail.
Gmail is currently applying a “temporary rate limit” to a network of IP addresses that includes the addresses of our server. This kind of limiting might occur when Gmail detects a high rate of spam from the source. Typically Gmail will single out individual addresses, but in this case it appears to be a larger block of IP addresses that includes some of our IP addresses that never ever send any email.
The issue is outside of our direct control and should clear up by itself soon. But in the meantime this is causing major inconvenience for our clients and we will continue to search for a work-around solution.
Update 4:25 PM UTC:
We are happy to report that email delivery to Gmail is back to normal.