We are using a Multisite installation and ran into two bugs with Postie:
The first is that Postie doesn't work with POP on Gmail. This was resolved by switching to IMAP, but I thought it was worth bringing up.
The second issue is that while Postie functions, when running it manually no information shows up. This shows what I'm talking about.
We have it working but would still like to have some debugging information when testing.