I need to know the IP block of their *outgoing* mail servers (specifically for Google Groups, but those mail servers probably cover their other services as well). We're running greylisting here at our ISP, and it's working fantastically -- but the delays it's causing to Google Groups e-mail notifications are giving one of our customers problems, so I want to preemptively whitelist their mail server IPs.
There's absolutely nothing relevant on their support pages (as might be expected). I can't get through to a live person at their corporate phone number. I just need a starting place.
(Comments to this post are screened in case you have a private phone number to give me. I'll update here if I can get things fixed.)
ETA: Possibly solved; see comments. (Fix time: 1/2 hour. I love the Internet.) Confirmation or further refinement would still be appreciated.