One of the big stumbling blocks was that I have a LOT of domains, all of which can receive mail. But, I just searched their help docs, and you can create domain aliases, so that solves that. No indicator of a limit on those, however.
The free version would be adequate in terms of storage, I think. My current archives are less than 3GB, and deleting the spam archive would kill a good chunk of that.
IMAP support would mean that my normal mode of use wouldn't see any change.
People who use alpine or such on rigel would see a difference, but I know alpine can work with IMAP.
Some of the routing controls and policy management might be useful, I don't know, but I'm not willing to pay $50/user/year for it. Not unless I kick everybody else off my domains, which wouldn't be very nice.
... oh ho. I read the help page about upgrading to premier, and it says you can add domain aliases to premier accounts. which implies you can't with standard. which it doesn't mention on the page /about/ domain aliases. awesome.
Hm. There are 11 mail spools on rigel. Some haven't changed in a very long time and can be deleted and ignored. some I know the user never looks at them, so I can probably blackhole them. So, I'm left with 5 to 7 people. Most of whom are probably not willing to pay $50/year for their email.