All MIME parts in a message (HTML text, plain text, attachments or whatever) are stored together by Mercury and extracted when needed. I'm not sure how Thunderbird handles attachments here though. It seems there might be some issues around, like those described here: https://getsatisfaction.com/mozilla_messaging/topics/attachments_missing_in_thunderbird_present_in_webmail

I sure hope this is possible.

What I'm trying to do is set up M32 on a Windows box on our network that can act as a local IMAP server to an existing bunch of Thunderbird clients. 

 M32 will not need to get mail from an outside source -- in fact I intend to only have one IMAP "user" or account. Since M32 allows multiple connections to the same IMAP account, this account can act like a public mailbox. Each TB client sends and retrieves mail from an outside server using individual accounts, but each TB client will also have the M32 common account -- so that messages can be dragged into it and others will have access to it.

 I've created a user in M32 named "common" and M32 runs on a machine with the ip 10.10.10.113 -- what do I need to set in TB to see this account?

I've tried entering the IP addy into TB for the incoming IMAP server hostname + various combos of port no., SSL and authentication, but I really don't need SSL or authentication as this is completely contained behind a firewall. 

 But nothing seems to work -- TB can't find a connection

 Hopefully someone has already done this and knows what to set and where to set it.

 I would love some help on this. 

 Thank you very much. 

Try connecting to the port that Mercury is listening on, usually 143, with Telnet to test connectivity (telnet 10.10.10.113 143). If you can connect continue with finding the right settings in Thunderbird, if you can't connect check routing and local firewalls.

Thank you, Rolf for your suggestions...

 I fiddled around and got TB working with M32 -- very nice and very fast. 

I can set up folders on the M32 IMAP server and connect to them with several instances of TB with no problems -- except one. 

 If a message with attachments is dragged into an M32 IMAP folder, the attachments are still shown as present, but when one tries to open an attachment to an email on the M32 server, Thunderbird reports that the attachment seems to be empty.

Yet, if one drags the email back to a "local" folder, the attachments can be opened just fine. 

Also, if one drags an email with attachments to a Gmail IMAP folder, the attachments open just fine from that folder as well. 

 So, is there some setting in M32 that needs to be set differently so that attachments on emails in an M32 IMAP folder don't seem to be empty?