I'd like to see the ability to alter the SQL selects mainly for userid and alias, placed in a config file.
The logic behind this is I would like to write some front end processing of the userid. For example, I would consider adding a status field to the dbmail_users table which I could then update with details like, “Account locked for non-payment”, “Valid”, “Account locked for suspected SPAM”, etc.
I don't expect DBMail to turn into a ISP user management tool, but I think almost every mail administrator has been required to user some valid/non-valid status on accounts.
By placing the queries in the config file there would be greater flexibility for the administrator.