The Postfix sendmail command has a -V flag to request VERP style
delivery. Specify one of the following two forms:
Postfix 2.3 and later:
% sendmail -XV -f owner-listname ....
% sendmail -XV+= -f owner-listname ....
Postfix 2.2 and earlier (Postfix 2.3 understands the old syntax
for backwards compatibility, but will log a warning that reminds
you of the new syntax):
% sendmail -V -f owner-listname ....
% sendmail -V+= -f owner-listname ....
The first form uses the default main.cf VERP delimiters, the
second form overrides them explicitly. The values shown are the
recommended ones.
