My Vigor 2910vg is operating in dual WAN mode - connected to 2 separate IPs. It has worked on email with no problem since installation 2/3 years ago.

I am now getting "550 relay not permitted" errors on Outlook and sometimes it becomes impossible to send any messages.

On reflection I am surprised I have not got this situation before...clearly Outlook can send messages via either IP though email is only registered with the WAN1 IP. When it (now?)goes to WAN2 this is seen as a relay.

I have not done anything to my set up....maybe one of the IPs has done something eg increased or restricted upload/download speeds

Whatever ...any suggestions as to how to configure the 2910 so that it always sends email via (in my case) WAN 1? Otherwise it is simply set for load balancing on both lines(and provide backup).

Tony