What can trigger MS Access autoexec vba macro?

I have this ms access database (.mdb) which contains an autoexec macro that runs a vba sub. It works, but I have a group full of users who are all saying they never open the .mdb file. There are DSNs that point to it. So when else can autoexec run (besides a user manually opening the mdb)?

These situations will trigger autoexec:

• Opening the .mdb directly
• Login script that opens Access
• Batch file that opens Access

The trick is the MSAccess application must run and open the MDB to trigger the autoexec.

A connection from another application through a DSN to pull data from a query within an MDB does NOT trigger an autoexec macro.