nnimap-expunge

nnimap-expunge is a variable defined in `nnimap.el'.
Its value is

t

Documentation:
If non-nil, expunge articles after deleting them.
This is always done if the server supports UID EXPUNGE, but it's
not done by default on servers that doesn't support that command.

This is a Gnus server variable. See Info node `(gnus)Select Methods'.