Mail Server suggestions

I’ve been spending a lot of time this week looking for and testing a number of email solutions. So far I haven’t found anything that does what I really want though. It’s also difficult to cut through all the crap that comes up no matter how carefully you craft the search terms. Basically, I’m after an email server package (reasonably priced or free) that can deal with the following: -

• Connect to Exchange server to collect/store off-line/send business emails + calendars + tasks
• Connect to customer’s mail server (POP3/SMTP/IMAP) to collect/store off-line/send business emails
• Connect to several personal email providers (outlook.com/gmail/yahoo/VirginMedia) to collect/store off-line/send personal emails
• Connect to Messenger 8 (RISC OS) locally to read/send personal emails
• Able to be accessed via client software on Android/Windows/Linux locally or over VPN when away from home
• Able to see each email account as a separate entity, not one big folder set and to send according to the mail account selected in the client
• Able to store emails off-line even when they disappear from the source email server, but able to delete from local store, and to move between folders
• Import and access locally archived Outlook and Thunderbird mail folders & calendars associated with the above accounts

I don’t really want it to act as SMTP server in its own right, but to connect to the relevant external server to send. As such I see it as an amalgamating server/store for the various sources, giving me a single server to connect the clients to. I’d like to host it internally on Windows Server or a NAS (QNap or Synology options), as these are the devices that are always on. Linux is also an option, but I’d need another computer to host it.

Currently in Windows I run Outlook for Exchange connection, Thunderbird for most of the personal accounts and my customer’s server, and Messenger Pro for Windows for connecting to the ARMX6 RISC OS version for the remaining personal accounts. I know some of these could be concentrated in Outlook, but that’s one of the things I’d really love to dump if feasible, and I’ve never successfully managed to connect to RISC OS Messenger from Thunderbird. Even MPro for Windows isn’t problem-free when connecting to MPro on RISC OS.

I’m probably looking for something that doesn’t exist! Any recommendations would be welcome though.

If Messenger can fetch all your accounts, Messenger Pro Server Edition will do the job. But it’s not on Store, so you’ll need to ask RComp directly.