Relaying disallowed only for some functions

Relaying disallowed only for some functions

Hello we setup correctly zoho mail with magento , everything is working ok.
However we have a marketplace module installed that the vendors communicate with the admins.
If a vendor need to send email to admin will get " Relaying disallowed  " and the message will not be sent.
Probably because trying to send from vendor email that is not on zoho smtp?

Is there a workaround for this please?

Kind Regards,
Alex