How to fix '550 Mismatching sender domains' error when setting up custom SMTP in Prestashop?

Email marketer from PrestaShop Forums suggests checking if the domain used in your email address is correctly configured in your PrestaShop settings, particularly in the 'Shop email' section. They note that an incorrect domain setting can lead to sender mismatch errors.

Email marketer from PrestaShop Forums recommends checking the SPF record for the sending domain. They explain that the SPF record must include the IP address or domain of the SMTP server you are using to send emails. An incorrect or missing SPF record can cause the '550 Mismatching sender domains' error.

Email marketer from Reddit suggests that the issue might be with reverse DNS (rDNS). They explain that the rDNS record for the IP address of your SMTP server should match your sending domain. If they don't match, some SMTP servers might reject your emails with a 550 error.

Email marketer from Webmaster Forum advises verifying that the SMTP server is configured to accept connections from your PrestaShop store's IP address. They mention that the server might be blocking the connection due to IP restrictions.

Email marketer from PrestaShop Forums shares to verify that the SMTP username and password are correct and have the necessary permissions to send emails. An incorrect username or password will cause the mail server to reject your sending request.

Marketer from Email Geeks suggests checking if the "Mail domain name" is allowed to relay through the custom SMTP server configured in the "Advanced Parameters - Email".

Email marketer from PrestaShop Forums suggests ensuring the sender domain is correctly configured and matches the domain used in your email addresses and SMTP settings. They emphasize that a mismatch can trigger the 550 error.

Email marketer from Stack Overflow mentions the need to set the `Return-Path` header to be the same as the `From` header. They explain that this helps the destination server correctly identify the legitimate sender.

Expert from Word to the Wise recommends checking for all references to IP addresses to confirm they are under your control, otherwise you may have difficulties.

Expert from Word to the Wise explains that a '550 Mismatching sender domains' error can be a sign of issues with email authentication protocols like SPF, DKIM, and DMARC, so it's worth taking the time to check this set of technologies.

Expert from Email Geeks recommends using `swaks` to test SMTP server configuration with configured domains and email addresses, focusing on MAIL FROM and 822.From headers. Example: `swaks --server your.smtp.server --to your.personal@email.address --from your.app@email.address` with appropriate authentication options. Further suggests to try different email addresses, analyze mail server logs, or use Wireshark to sniff traffic.

Documentation from Microsoft indicates that a 550 error (specifically 550 5.7.1) often means the sender is blocked. Steps include checking if the sending IP is on a blocklist, ensuring proper SPF/DKIM/DMARC settings and contacting the recipient's email admin for whitelisting.

Documentation from cPanel explains that '550 Mismatching sender domains' typically indicates an issue with email authentication. It recommends ensuring that your SPF, DKIM, and DMARC records are correctly configured for your sending domain to improve email deliverability and prevent this error.

Documentation from AWS explains that a 550 error could be the result of you exceeding sending limits. It is possible your email sending service provider has placed a limit on sending and it might be the cause.

Documentation from RFC Editor says status code 5.7.1 is "Delivery not authorized, message refused". Contact your email provider.

Documentation from SparkPost mentions that the error '550 5.7.1 Sender address rejected: not owned by user' indicates that the sender address is not authorized for use with the provided SMTP credentials. It suggests verifying the 'From' address and ensuring it matches the authenticated user.