GMS List Server or GMS Communication Server could not deliver a message so it is being returned and the list membership database will be updated. There are three reasons why the message may be returned undelivered:
- Can’t deliver. GMS List Server or GMS Communication Server has been attempting to delivered the message for nearly 72 hours and the remote server has not become available to accept the message;
- Can’t resolve. The domain name does not resolve into an IP address using MX or A records.
- Unknown account. The remote system says that it does not have an account with this name.
In this case session Undefined can’t deliver a message to Undefined on the list Undefined. The message can’t be delivered because "Undefined".
GMS List Server or GMS Communication Server has processed the message so there is no action required by you.