Why are Gmail emails bouncing with '553 5.1.3 The recipient address is not a valid RFC-5321 address' error?

Email marketer from Reddit explains that this error usually points to a problem with your data, like a copy and paste error or a system glitch and suggests cleaning your email list to ensure all addresses are valid and correctly formatted.

Email marketer from StackExchange recommends identifying any special characters within the email that are not compliant to RFC 5321 and ensure they are corrected to remove errors.

Email marketer from Litmus advises maintaining good list hygiene by regularly cleaning your email list to remove invalid or inactive addresses, reducing bounce rates and improving deliverability.

Email marketer from EmailToolTester shares that the '553 5.1.3' error is due to an invalid email address. It could be a typo, an unsupported character, or extra spaces. Suggests double-checking the email addresses in your list for errors.

Email marketer from Stack Overflow user suggests using online tools to validate email addresses before sending and check your system to see if you are adding a space.

Email marketer from Email Geeks shares a similar experience and recommends looking for special characters like ” in the from name, not address.

Email marketer from Sendinblue recommends using an email validation service to automatically detect and remove invalid email addresses from your list, ensuring better deliverability and sender reputation.

Email marketer from Mailjet mentions that '553 5.1.3' indicates a syntax error in the email address. Suggests implementing email validation at the point of entry (e.g., signup forms) to prevent invalid addresses from entering your system.

Email marketer from Email Marketing Forum suggests checking for common errors like typos, extra spaces, or invalid characters in the email addresses. Also, ensure your email sending system is not automatically adding any formatting that violates RFC 5321.

Expert from Spam Resource explains that the '553 5.1.3' error often stems from an invalid email address format, highlighting the importance of verifying the syntax of email addresses before sending. Common issues include invalid characters, spaces, or incorrect domain formatting.

Expert from Email Geeks suggests checking how the email addresses are stored, suspects the issue is with the email addresses stored incorrectly, and until recently either the ESP was cleaning them on send, or Gmail was accepting invalid addresses. He also provides a telnet example showing the error when a space is included in the recipient address.

Expert from Word to the Wise advises implementing robust email address validation techniques to catch invalid email address formats before sending. This includes checking for proper syntax, valid domain names, and other common errors that can lead to bounces.

Documentation from IETF refers to RFC 2822 (which was superseded by RFC 5322, but contains related information on email address format) which provides details on valid characters and syntax for email addresses. Proper formatting is crucial for email delivery.

Documentation from Microsoft Support explains that email addresses must conform to Internet standards, including RFC specifications. Invalid characters or formatting can cause rejections by mail servers like Gmail.

Documentation from RFC Editor refers to RFC 5321 section 4.1.2 which specifies the syntax of email addresses, including restrictions on allowed characters and formatting. Addresses must adhere to this standard for proper delivery.

Documentation from Google Workspace Admin Help explains that this error means the recipient's email address doesn't conform to the RFC 5321 standard, which defines the valid format for email addresses. This can include invalid characters, incorrect syntax, or leading/trailing spaces.