How to Fix error 550 Error – postfixs email rejected with forged ehlo/helo error 550

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Postfix email rejected with forged EHLO/HELO error 550, how to fix?

The Problem

Postfix is rejecting emails with a forged EHLO/HELO error code 550, despite correctly configured IP addresses and domains. This issue affects email senders who have multiple IP addresses and domains set up in their Postfix configuration.This problem can be frustrating for users as it may lead to undeliverable emails or difficulties when sending emails through their server.
🔍 Why This Happens

                The primary reason for this error is that Postfix does not correctly verify the sender's domain during the EHLO/HELO process. This can happen if the `smtp_helo_name` parameter in the master.cf file is not set correctly or if there are issues with DNS resolution.Another possible cause could be a misconfigured `smtp_bind_address` parameter, which may lead to Postfix responding with an incorrect IP address during EHLO/HELO.

            🔧 Proven Troubleshooting Steps

                Verify and correct the `smtp_helo_name` parameter

                    Step 1: Check the value of the `smtp_helo_name` parameter in the master.cf file to ensure it matches the expected domain. If necessary, update the parameter to use the correct domain.Step 2: Run the command `postfix checkhelo` to verify that Postfix is correctly using the specified domain during EHLO/HELO. This can help identify if there are any issues with DNS resolution or the `smtp_helo_name` parameter.



                Verify and correct the `smtp_bind_address` parameter

                    Step 1: Check the value of the `smtp_bind_address` parameter in the master.cf file to ensure it matches the expected IP address. If necessary, update the parameter to use the correct IP address.Step 2: Run the command `postfix checkbind` to verify that Postfix is correctly using the specified IP address during EHLO/HELO. This can help identify if there are any issues with the `smtp_bind_address` parameter.


            ✨ Wrapping Up
            To resolve the issue of forged EHLO/HELO error code 550, it is essential to carefully verify and correct the `smtp_helo_name` and `smtp_bind_address` parameters in the master.cf file. By following these steps, you can ensure that Postfix correctly verifies the sender's domain during EHLO/HELO, resulting in deliverable emails.

Full step-by-step guide with screenshots: Read the complete fix here

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