This is not an error message from Mercury but from the receiving SMTP server.
There are two ways to change how messages are sent to list members. In Distribution you can have Mercury create up to 20 separate jobs for delivery ("fanout"), in Error handling you can select VERP-based to have separate delivery for each member. From Mercury help:
"VERP-based error handling VERP stands for "Variable Envelope Return-path Processing": when using this method, every recipient in the list gets a separate copy of every message sent to the list, and in that copy of the message, a special version of the Return-path field is created that allows Mercury to work out the individual list and subscriber from any errors that get returned to it."
/Rolf
<p>This is not an error message from Mercury but from the receiving SMTP server.</p><p>There are two ways to change how messages are sent to list members. In Distribution you can have Mercury create up to 20 separate jobs for delivery ("fanout"), in Error handling you can select VERP-based to have separate delivery for each member. From Mercury help:</p><p>"VERP-based error handling &nbsp; VERP stands for "Variable Envelope Return-path Processing": when using this method, every recipient in the list gets a separate copy of every message sent to the list, and in that copy of the message, a special version of the Return-path field is created that allows Mercury to work out the individual list and subscriber from any errors that get returned to it."</p><p>/Rolf&nbsp;</p>