I know that the first thing that will happen when I enable IMAP access to voicemail is that people will hit the reply button and try to reply. What options does Connection offer? Will it accept email? Will it accept wav attachments? I tried replying but I don't see the message anywhere. I've added the IP addresses to the access list.
I assume you're running 7.0 here...
You can enable an option to try and play attachments in the after message menu - this is done with the Custom Key Map tool, it's not an option in any of the "out of the box" conversations. Go to the CKM tool on the SA, have it import the conversation options from the conversation you're doing (say the standard conversation) and then in the after message menu tab map the "Play Message Attachments" option to a key press.
Map one of your test users to that conversation and give it a whirl.
If it's a text based attachment, it'll try to TTS it, if it's a WAV file it'll try and play it and so on.
Be aware that the codec support on the Linux based Connection is a bit more restrictive than the Windows based Unity - when testing stick with G711 MuLaw if you can (although G729a and PCM is supported). If it can't play it for whatever reason it'll say that it can't play the attachment after telling you what it is.