How a public domain sender address affects email deliverability

How a public domain sender address affects email deliverability

Whenever you send campaigns, they will be delivered to the receiving server of the respective mailbox provider. The receiving server will offer inbox placement after carefully scrutinizing the email. If the emails are from a source that the mailbox provider doesn't recognize or considers suspicious, the receiving server may reject them.
Mailbox providers consider a lot of factors before making inbox decisions. The sender address is one of those factors that plays a huge role in determining inbox placement for your campaigns. There are two types of domains from which emails are being sent.
Public domain: A public domain email address is one provided by free email services such as Gmail, Yahoo!, AOL, Outlook, etc.
Business domain: A business domain email address is one used by business to send marketing emails, newsletter and transactional emails. Example: A company called Zylker Financial might use addresses like

At Zoho Campaigns, we strongly urge our users not to use a public domain sender address to send marketing emails as it will lead to deliverability issues. Let's dive deep and learn more about the drawbacks of using a public domain sender address and how it affects email deliverability.

Implementation of DMARC by mailbox service providers 

DMARC (Domain-based Message Authentication, Reporting, and Conforming) is a security mechanism that you can implement to prevent spammers from using your sender domain to perform phishing and spoofing activities. Most mailbox providers have started implementing DMARC to safeguard their sender domain.
DMARC can be implemented only for a business domain sender address and not a public domain sender address. Implementing DMARC eliminates the probability of fraudsters using the sender domain of a business to perform phishing and spoofing activities. When making inbox decisions, mailbox providers give additional weight to emails from a business that has implemented DMARC.

How Gmail reacts to emails sent using a public domain

Gmail pushes emails from public domain addresses to the spam folder and warns recipients with a message that they were unable to verify the sender domain:

Recognition and trust 

Whenever people receive an email, the first thing they notice is the sender address. When they recognize the sender, they're more likely to open the email. When people receive marketing emails from a public domain sender address, they may become hesitant to open it. There are chances for them to mark the email as spam.
For example, if recipients receive an email from, they are likely to wonder about the email's origin. On the other hand, if the sender address is, the recipients can immediately recognize that the email comes from the company Zylker, and this familiarity will help them trust the domain. So we always urge our users to use a business domain sender address to send their campaigns.
If you use a public domain sender address to send marketing emails, your contacts are more likely to leave your email unopened. Nowadays, mailbox service providers consider email engagement to make inbox decisions. If mailbox service providers identify that your emails are left unopened, they may assume that their users are not interested in receiving your emails and may deny inbox placement for your future emails. The only way to achieve the desired conversions is by using a business domain sender address and authenticating it.
Click here to learn more about sender recognition.

How Zoho Campaigns handles a public sender domain address   

If you try to add sender addresses from public domains in Zoho Campaigns, the system will alert you. Here's an example:

Using a public domain sender address
  1. Log in to your Campaigns account.
  2. Click the Create button and then click Email Campaign.
  3. In the Sender list box, click Add sender address.
  4. Enter the email address and click the green tick button. If your email address is from a public domain (for example,, you will see the error message "Use your domain-specific email address"

Using a public domain reply-to address 
  1. Log in to your Campaigns account.
  2. Click the Create button and then click Email Campaign.
  3. In the Reply-to Address list box click Add sender address.
  4. Enter the email address and click the green tick button. If your email address is from a public domain (for example,, you will see the error message "Use your domain-specific email address"
  5. If you add other public domains as a sender address (Gmail, Outlook, etc.), you will be prompted to use your own domain address instead:

Lets examine another scenario to understand what happens if you try to add a public domain email address through Settings:
  1. Navigate to Settings and select Manage Senders.
  2. Click Add Sender in the top-right corner of the page. You'll see the following error message: Avoid using Yahoo/AOL-based sender address. "Use your domain specific email address."
Since Yahoo! and AOL have already restricted the use of their domains to send emails from other servers, other public email services will likely follow suit. That's why we recommend you to not use any public domain email address.

Wrap up 

If you use a public domain sender address, you may face the following issues:
  1. Your emails may bounce, as major mailbox service providers have implemented DMARC
  2. Your emails may resemble spam, as spammers use public domain sender addresses to send junk email
  3. Your recipients may not recognize your business
  4. Your emails may be left unopened and you won't be able to achieve the desired conversion
  5. Sometimes your emails may get marked as spam. This will affect deliverability for your future emails

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