I'm (happily) out of the 1065 business but a preparer on another list mentioned that he's going to take the opportunity to solicit change of address/email address info from clients' partners in the same communication as this.  No idea how he plans to generate the letters, I assume with some sort of mail merge outside of tax software.

Seems like an opportunity for billable hours at the end of December/beginning of January.  (Holidays?  What are those?)