Are you going to be hosting Windows and Android clients? That would be the deal breaker. MS Outlook 2007-2010 is a pain in the butt to get working for IMAP and I just tested Outlook 2013 the other day-- STILL no CalDAV/CardDAV support (calendar/contacts) but IMAP mail went fine. On some Windows XP machines I used Mozilla's Thunderbird for email and the Lightning plugin for CalDAV/CardDAV, and it was a hassle, but it worked to the Apple Mail server. The Android devices have never worked for me syncing to Apple Mail server. Whether it is because of protocol mismatch, authentication scheme mismatch or just that we had self-signed certs on the service.
Combine that with (Apple's unspoken technology roadmap) the sudden unexplained loss of WebMail in Mountain Lion Server, and I'd steer you toward Google Apps. Apple doesn't really let you downgrade to past operating systems like Lion, and even if you found a way, that isn't really a supportable principle going forward because you are locked out of upgrades. I think Apple is killing those features in the product, and they want you to steer to cloud resources.
All that being said, If you have an All-Apple ecosystem like I do, Apple's mail/calendar/contacts server functionality have worked flawlessly for the last three years from my Snow Leopard macmini server and even though I hardly ever use WebMail, it has been a lifesaver when needed.
Thanks for the info.
Does Lion Server just use IMAP then? I use IMAP now for my personal email and the inbox syncs but doesn't seem like sent or deleted messages do. That is an all apple environment.
I host my own domain on a web server so I'll have to point it to my local Lion Server. Guess only pain would be dynamic IP but I don't lose it often.
As far as clients, I am almost all Apple but do have some proprietary software that sits on a PC. Although, If I do this that PC would become a MAC with VMware running the Windows side so can use the Apple mail client. Switched all my workers to iphone so really no need to go outside the Apple environment.
Glad to help.
Lion Server can do POP and IMAP for pulling messages to clients (and SMTP for sending to the server from clients).
IMAP does sync all folders, so you may actually be having a problem with your current IMAP service if it isn't syncing sent and deleted, etc... IMAP also allows you to create new mail folders which are stored on the server and get replicated to all your devices.
As far as having a dynamic IP: that isn't ideal, because you may get blacklisted by other mail services. You also get auto-blacklisted if you are using a traditionally home-user type service like Qwest DSL. I've had that happen on a few clients and we had to do a little work to get it cleared up.
If possible, I'd recommend buying a static IP- many providers charge $5-6 per month to have a dedicated IP on your router. However, if changing to static isn't an option, there is a dynamic DNS service to help keep your mail server connected to the world when the public IP on your router changes:http://dyn.com/dns