[exim] Relay Not permitted

Hi All

Iam running exim-4.83-3.1.8.x86_64 on my relay server. One client who
relays through my server has issues with receiving mail from a particular
domain.


My relay server rejects the email with error


*"F=<xxx@??? <xxx@???>> rejected RCPT
<yyy@??? <yyy@???>>: relay not permitted".*

Any pointers on how to get tis fixed?.

Regards
Ritah