Causes of Hard Bounces

Hard bounces occur due to reasons that typically involve permanent conditions or errors within the recipient's email system or address. Some common causes include:

• Invalid Email Address:

  • The email address does not exist or is incorrectly formatted (e.g., missing "@" symbol, typos).

  • Example: john.doe@example.com (where example.com is not a valid domain).

• Domain Does Not Exist:

  • The domain part of the email address (e.g., example.com) does not have valid DNS (Domain Name System) records or does not exist.

  • Example: john.doe@nonexistentdomain.com.

• Recipient Email Server Error:

  • The recipient's email server is unreachable, or there are DNS issues preventing the email from being delivered.

  • Example: Email server for example.com is temporarily down or unreachable.

How Hard Bounces are Handled:

When an email is hard bounced, email servers typically generate a bounce message (also known as a Non-Delivery Report or NDR) and send it back to the sender's email address. The bounce message informs the sender's email server about the delivery failure and provides details about why the email could not be delivered.

Examples of Hard Bounces

• Invalid Email Address:

  • Scenario: A user mistypes their email address when signing up for a newsletter, entering janedoe@gmial.com instead of janedoe@gmail.com.

  • Result: The email server attempts to deliver the newsletter to janedoe@gmial.com, but since gmial.com is not a valid domain, it hard bounces.

• Nonexistent Domain:

  • Scenario: A company sends promotional emails to an outdated email list that includes addresses from a domain they no longer use, such as sales@oldcompany.com.

  • Result: The email server attempts to deliver the promotional email to sales@oldcompany.com, but the domain oldcompany.com no longer exists, resulting in a hard bounce.

• Blocked Email Address:

  • Scenario: A recipient's email address is flagged and blocked by the email provider due to suspected spam or security concerns.

  • Result: Emails sent to that address consistently result in hard bounces due to the recipient's email provider blocking the delivery.

Impact and Importance

• • Email List Hygiene: Managing hard bounces is crucial for maintaining a clean and accurate email list. Continued sending to addresses that hard bounce can negatively impact sender reputation and deliverability rates.

  • Compliance: Maintaining low bounce rates is essential for complying with email marketing regulations, such as the CAN-SPAM Act in the United States, which requires senders to honor unsubscribe requests promptly and manage bounce rates effectively.

  • Sender Reputation: High bounce rates, particularly from repeated hard bounces, can negatively affect sender reputation with email service providers (ESPs), potentially leading to emails being filtered into spam folders or outright blocked.

Best Practices for Handling Hard Bounces

• • Monitor Bounce Rates: Regularly monitor bounce rates to identify trends and patterns in email delivery issues.

  • Remove Hard Bounced Addresses: Promptly remove email addresses that hard bounce from your mailing list to maintain list hygiene and improve deliverability rates.

  • Verify Email Addresses: Implement email validation processes during signup to minimize typos and ensure email addresses are correctly formatted.

  • Update Email Lists: Regularly update and cleanse your email lists to remove inactive or outdated addresses that may result in hard bounces.