You can add many sending addresses from different domains. You also have the option of adding and validating an entire domain. This option is only recommended if you have many sender addresses to add from one domain and you want to save time by not manually validating each one.
To view your sending addresses and domains, click on My Account → Add a Sender Domain or Address.
them, it's necessary to validate this address individually for each API key.
To add a new sender address, click ‘Add a Sender Address’.
Fill in the fields, then click the ‘Add’ button to continue.
A message will appear stating that a confirmation email has been sent to your new sender address. Go to your mailbox, and click on the confirmation link within this email to activate the new sender address.
Once activated, you will see the ‘Active’ status.