Patrick, Law has the same concerns about email archives but not specifically to the email limit. Our faculty also have email archives (both in .pst and online, as we are an Exchange shop) that span decades. My concern is more about who is responsible for migrating/importing/organizing the multiple archive files. Each faculty member has their own method for organizing their archive files. Some archive based on calendar year, some on academic year, some on email age, etc. They will absolutely want the same organization no matter what the email system. They won’t be happy if archives are actually just folders in their inbox. Some even store their older .pst archives on CD…available but not part of their mailbox.
Law provides our graduates with a permanent @alumni.law.unm.edu email account for the same reasons you state. Since our email environment is mature (Exchange 5.0 installation in 1998 or 1999 but VMS mail before that), we believe our needs are specific to our current use and are working on generating a law-specific SLA.