I assume facebook has both [email protected] and [email protected] so that their employees don't get their own outgoing emails blocked as spam the same way that "Bob sent you a message on Facebook!" messages might.

However, I am guessing that my notifications might be likely to be tagged as spam if notifications come from startupmail.com and those notifications contain links to startup.com (or a reply-to: to [email protected]).

Any experienced insights much appreciated!

EDIT: Any thoughts on the variant of having [email protected] and [email protected], and the effect of a spam rating of the subdomain on the main domain?