Email Authentication: Sender Emails and Fallback Domains

This article explains the importance of using a business domain email, not a personal email address as your sender email.

As of February 2024, Google and Yahoo have increased their enforcement of domain authentication. To avoid issues with email delivery, it’s crucial to complete DKIM and DMARC authentication for the domain you use to send emails.

Freemail Addresses

A “freemail” address is an email with a domain owned by an ISP, not your organization. For example, an email address with the domain @gmail.com, @yahoo.com, or other related domains is considered a freemail address. Ultimately, if you or your organization do not own the domain you are sending from, then you’re probably using a freemail address.

Occasionally, inbox providers like Google or Yahoo, change their authentication records for their domains. This negatively affects the deliverability of anyone who uses freemail addresses as their sender email when sending from an email service provider (ESP).

Using a Unique Domain for Your Sender Email

If you are currently using a freemail address as your sender address, you will need to change it to an address with a unique domain owned by you or your oganization. For example, [email protected] instead of [email protected]. Otherwise, your email deliverability rates will suffer and your campaigns may never make it to the intended inboxes.

If you do not currently own a domain or if you’re not sure what that means, please refer to our Domain Names and Registrars article.

Fallback Domain

Warning: If you continue using any freemail address as your sender email, you will be required to use a unique, system-generated fallback address when you send a campaign.

The fallback process converts a freemail address such as [email protected] to the.company.yahoo@#.e2ma.net. The # represents an account-specific subdomain to help improve delivery and so we can monitor bouncing. Replies to that fallback address will still go to [email protected].

Information about the fallback process can also be found in the warning that appears on the Review & Send page. This warning does not prevent you from sending.

The fallback process is designed to help you avoid the immediate, serious deliverability issues that are caused by sending from a freemail address. However, you will need to inform your recipients ahead of time so that they can add this temporary address to their address books.

Note: The fallback process is not a permanent solution. Ultimately, you must update your sender email to a domain that you own and have authenticated.

Unauthenticated Private Domains

If you are sending from a domain that you own, but you have not yet set up DKIM and DMARC, then you will also see the fallback sender warning on the Review & Send page. However, unlike those sending from freemail addresses, you can choose to not use the fallback domain. If you do not want to use the fallback domain, you must uncheck the box in the fallback sender warning. This much be done for each individual campaign that you send until you set up DKIM.

Frequently Asked Questions About Sender Emails and Fallback Domains

Can I ignore the sender address warning?

No, the fallback is required for anyone who is sending from a freemail address. If you are sending from a domain that you own, but have not authenticated yet, then you may choose not to use the fallback domain. However, you must make that selection each time you send a campaign and we recommend that you set up DKIM and DMARC as soon as possible.

What is DMARC and how does it factor into deliverability rates?

Inbox providers use an authentication technology called DMARC, which combines DKIM and SPF to give more comprehensive protection to a domain. Yahoo, for example, has set one parameter of DMARC to tell all mail servers that if DMARC authentication fails for yahoo.com, the message should be rejected. At this time, any mail server checking for DMARC authentication will refuse any message sent through an ESP using a yahoo.com email address as the sender.

Some major inbox providers now also require that anyone sending through an ESP have DMARC set up on their domain. To prevent potential deliverability trouble as a result of this requirement, we strongly recommend that you set up DMARC and DKIM, at minimum. For more information about DMARC, check out our DMARC Authentication Setup article. For more information about authentication requirements, check out our Email Authentication: Overview article.

How do I help prevent future issues?

Once you change your sender address to a branded domain you manage, you will need to set up a DMARC policy and DKIM-signing in your account. Please check out our Email Authentication: Overview article for more information.