You can add up to 100 senders per API Key. A sender can either be a manually validated sender address or a sending domain.
While each API Key can only have one custom Return-Path and one custom tracking host, this does not limit the use of multiple sender domains. As long as the DKIM (DomainKeys Identified Mail) is correctly configured for each sender domain, emails sent from different sender domains than the ReturnPath domain will still be authenticated and delivered successfully.
Recommendation: If you want full alignment between the sender domain and the ReturnPath and/or customized tracking host, consider using multiple API Keys for each domain. This allows you to assign a unique ReturnPath and tracking host for each sender domain, ensuring complete consistency.
The Sender Domains & Addresses page will list all current sending domains and (manually validated) sender addresses. The total declared senders is the sum of the domains and the sender addresses (regardless of status).
From the example above, this account above has 2 declared senders:
-
1 validated domain (*@mywebsite.com)
PLUS - 1 manually validated sender address (xxx@mywebsite.com)
Sender addresses tied to a validated domain that have not been manually validated (do not appear in the Addresses table) are not counted toward the sender limit. Using the example from above, you can send from various @mywebsite.com email addresses (sofia@mywebsite.com, paul@mywebsite.com, ...) and it will not affect the declared sender limit.