Hello.
Nancy, as I see you know much more than me about mail programs and use them professinally. Unfortunately I still haven't so many exprience in mail processing sofware to give detailed answers.
Here is what I know at the moment
1. We use UW-imap server (http://www.washington.edu/imap/).
2. It is provide APOP and CRAM-MD5 authentication
(http://www.washington.edu/imap/documentation/md5.txt.html)
3. I don't know what do you mean. Why do you need the name of the imap server to connect through telnet to it? You can simply connect at
telnet 209.51.138.26 143
4,5 Yes, we have procmail 3.21 installed
6. Our Pine is 4.44 version.
7. This is mostly depends from privileges that program requires to be installed. In any case we are always ready to help users in the updating, configuring and installing additional sofware if it is need root access for it.
8. We use our own scripts for making backups and we do this weekly. We store two last backups on other our servers. You need ask me to make restore of your files.
9. Mmmm hard question. We haven't provide such ability until this time. But if you need it and help us to set up this we will do.
Anyway as I see you need test our server to give exact answers on all questions. I can give you a test account for some days. I hope it will help you to make final decision and buy our hosting