Control access to your account's sending via SMTP relay by specifying allowed From Addresses.
When you define allowed From Addresses for an account, sending from any unlisted From Addresses will be denied.
To restrict sending by From Address:
- Go to Settings > Transactional Settings > From Address Restriction
- Click Add New Item > specify which email addresses and domains can send through the relay. By default, all email addresses and domains can send through the relay
- If you wish to restrict the use of the relay to an entire domain, you can use the wildcard notation *@domain.com as the From Address to represent all addresses for domain.com.
If there are no From Addresses entered, as is the default on accounts, then there are NO restrictions on which From Addresses can send through your account. As soon as you enter at least one From Address, then that becomes the From Address(es) from which your account must send.
If a user attempts to send through SMTP relay from an unauthorized From Address, you will get a SMTP Relay Error that says "This From Address ("XXXX@XXXXX.com") is not allowed to send through this account.".
Note: Specifying From Address restrictions only apply to emails sent through the Relay, and not through the transactional email API.
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