How quickly user acts on an incoming email. This is calculated from the time the user's IMAP connection has seen the new message and FETCHed its metadata. This may be a long time after the actual mail delivery in case all users don't have active IMAP connections all the time.
Deliveries per second is roughly defined by total_user_count divided by this value. If using multiple user profiles, deliveries per profile will need to be reduced based on the user profile's count value.
Default: <none> (either this setting or userfile must be set)
Username template format.
%n expands to the user index number. See username_start_index. Padding can be defined by specifying <padding character><padding length> after the '%'.
Example: username_format = firstname.lastname@example.org means that the calculated index will be padded to 3 numbers (with 0's). If total_user_count = 500, the generated users would be email@example.com to firstname.lastname@example.org.
The first index number to use for users in this profile. Usually different user profiles should either not overlap or overlap only partially (to describe users who have different behaviors with different clients).