It seems like impossible but we have 2x companies with @abc.com and @xzy.com as their respective email domain names in separate O365 tenancy. Is it possible to add a common email domain name for staff of both companies called @pqr.com such that:
1) amy in abc company has email address amy@abc.com and amy@pqr.com
2) tom in xyz company has email address tom@xyz.com and tom@pqr.com
An outsider can send email to amy@pqr.com and still reach her mailbox at @abc.com O365 tenant. Likewise, the same for tom.
Any suggestions?