Returns a single integration mailbox by its id (from List Safety Net Mailboxes), with its Safety Net state (activated) and the sales-engagement integrations it appears in.

A 404 means the id isn't among your synced integration mailboxes — note that a mailbox can be connected to Allegrow without appearing here (see Overview on the two mailbox populations), and connected-mailbox ids are not interchangeable with Safety Net mailbox ids.

Entries with id: null — possible briefly for a newly synced mailbox — can't be fetched individually; refetch the list to obtain the id.