What does it mean to have the domain set as the "Default" sender? It is good practice to have a default verified sender domain. When there is a default domain set on the account, emails are still branded using the default domain, even if sent from a non-verified domain. This is particularly important if sub accounts are using the main account's sender domain or for resellers that want notification emails to send using their domain.
If there is no default domain set, and an email is sent from a non-verified domain, then elasticemail.com is used.
When a default domain is set, then sub accounts will inherit the ability to use the main account's default verified sender domain. The default sender domain of a main account is visible on all subaccounts. It can be used by them, but not modified in any way.
If an account does not have subaccounts, verifying a default sender domain is still beneficial. It lifts the 500 emails per day sending limit and helps the account be identified as a legitimate sender.
An account without a default sender domain also has lowered deliverability performance as some inboxes will not recognize such account as a legitimate sender.
You can set your domain as the default sender on your Settings>Domains screen:
You will know the domain has been set as the default successfully when the star beside it's name turns blue.
You can find out more about verifying domain in our other article How to verify your domain