A public domain email address is one provided by free email service providers such as Gmail, Yahoo!, AOL, Outlook, etc.

How it affects your email deliverability 

• Recognition and trust
  
  Email recipients look at who sent the emails they receive. When they easily recognize the sender, they're more likely to open the email. An email from a public domain sender address may make recipients hesitate to read your email, and they may even mark it as spam.  If the recipients receive an email from patricia.b@gmail.com , they are likely to wonder about the email's origin and may mark it spam. On the other hand, if the sender address is patricia.b@zylker.com , they can immediately recognize that the email comes from the company Zylker and this familiarity will help them trust the domain. To learn more about sender recognition, click here .
  
• As spammers often use public domains for their sender addresses, the domain reputation for these domains tends to be low. Using a free domain sender address gives a high chance that your emails will be classified as spam or junk. 
  
• To prevent spam messages getting through, many email services follow DMARC policy to protect their domain reputations, which means that when you use public domains, there is a risk that emails will be bounced.
  
• Using a public domain address to send emails does not reinforce your brand presence to your recipients.
  

Restricted public domains

Yahoo! and AOL have restricted the use of their domain addresses for sending campaigns, as they've made changes to their DMARC policies for security reasons. They’ve instructed other email service clients to reject the emails that come from Yahoo/AOL sender addresses but not through Yahoo/AOL servers. If you try to add sender addresses from public domains in Zoho Marketing Automation, the system will alert you. Consider the scenario below:

1. Add a new sender address by clicking on the dropdown in the Sender Address tab.
   
2. Click the Add sender address button.
   
3. Enter the email address and click the green tick. If your email address is from a public domain (for example, patricia.b@yahoo.com ), you will see the error message "Use your domain-specific email address".
   

If you add a public domain reply to address, you will see the same error message:

Why email services chose to tighten their DMARC policies

Due to increasing email-based spam aiming to acquire sensitive information (such as credit card details), email service providers made a few changes to their policies to increase email security by complying with DMARC policy. These changes help ensure that only emails from genuine senders reach the recipients' inboxes.

Anyone can use a public domain to send emails, including spammers, while genuine marketers should have their own business domain to send emails from.

How Gmail reacts to emails sent using a public domain 

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

Manage your sender address

• Add and verify your business domain sender address in your Zoho Marketing Automation account.
  
• Authenticate your domain with SPF and DKIM.
  

Best practices

If you use your own business domain, the reputation of your domain, and therefore your email deliverability, will depend only on your own sending practices, and not on a public domain's reputation. Using your own business domain helps promote trust, familiarity, and easy recognition among your leads, and helps you improve and control your email deliverability and increase business.