Make sure this is an indexed list and has an ezmlm-get line first in DIR/manager. If not, your commands are fed directly to ezmlm-manage(1). If they contain ‘-’, ezmlm-manage interprets the rest as an address to which it sends the error message. Usually, this results in a “trash address” mail log entry and a bounce, which is why you don't see any error message. The same happens if you send non-existing commands followed by ‘-’ and arguments. Thus, ‘list-gugu-54@host’ results in an ezmlm-manage error, resulting in help text being sent to ‘54@localhost’ When testing, try using syntax with a ‘.’, not a ‘-’, after the action command, e.g. ‘list-get.54_60@host’. This will assure that error messages get back to you.