Allowed Sender Address
By default, any email addresses from a registered domain can be used as a sender address. But during the Implementation phase, it is possible to define a restricted list of email addresses that can issue an email through Transactional Email service. This has been meant to increase security and prevent misuse of a sender domain. Here are the prerequisites for using this feature:
Ask to enable this feature during Implementation or by opening a Service Request.
Allowed email addresses must match the registered sender domain.
A maximum of 50 different email addresses per sender domain can be configured.
Role-based addresses are forbidden (see “Prohibited role-based Sender & Recipient Names“ section).