Hi there,
I know you can migrate an SV8100 database to an SV9100 processor. However, can I backup the InMail on the SV8100 and retain everyones mailbox settings, greetings, etc?

The only way I can think to do it is to login with USER1 and manually download EVERY greeting, and re-upload again manually to the SV9100

Never tried it. Always have them go through the procedure again to at least get it fresh in their minds again. I know the databases will, but depending on the size of the install seems like an awful amount of hand wringing and work for nothing.