Ive seen a couple of posts around this topic but never really found an answer that fits my scenario.
We have our tenant (TenantA.com for the purpose of this discussion) and we recently acquired another org, so we now have TenantB.com - there are plans eventually to merge tenants, but thats quite a while away just now.
Ive been asked to provision email addresses using our primary company email domain on TenantA.com - which will forward mail across to users on their TenantB.com address.
Im running into issues because a considerable number of users have been added to a variety of teams and Sharepoint resources in our Tenant A - thus creating "Guest Mail Users" - the number of resources that have been shared are likely too many to re-create at this stage.
Whats the appropriate way for me to set up a forward email address in this instance?