553 Recipient unknown error on GWIA while sending a mail to the Distribution List

553 Recipient unknown error on GroupWise Internet Agent (GWIA) while sending a mail to the Distribution List

550 No such recipient

GWIA does not allow inbound mail sent to Distribution lists

GroupWise users can send messages to the Distribution List internally
How to allow external users to email a DL (what to configure)

2. Right click on the GWIA object properties

3. Click on SMTP/MIME tab | Address Handling

4. Check the "Expand distribution lists on incoming messages" options in Inbound Settings and click Apply and OK.

By default, GroupWise Internet Agent (GWIA) ignores email addressed to distribution lists (groups). Enabling the "Expand groups on incoming messages" options allows GWIA to recognize distribution lists (groups).

GWIA will not expand the group itself, but pass it to the Message Transfer Agent (MTA). The MTA will then correctly deliver the message to the members of the distribution list.

See Documentation Section 53.1.3, Configuring How the GWIA Handles Email Addresses.