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Fixing “Must issue a STARTTLS command first” Error in Postfix Using Gmail Relay

Ubuntu 20

In the world of email servers, encountering errors is a common occurrence. One such error that you might come across when using Postfix with Gmail as a relay is the “Must issue a STARTTLS command first” error. This error is indicative of Postfix’s inability to establish a secure Transport Layer Security (TLS) connection with the Simple Mail Transfer Protocol (SMTP) server. This article will guide you through the process of resolving this issue by correctly setting up your Postfix configuration for TLS encryption.

Quick Answer

To fix the "Must issue a STARTTLS command first" error in Postfix using Gmail relay, you need to ensure that your Postfix configuration is correctly set up for TLS encryption. This involves verifying and configuring the necessary settings in the main.cf file, creating a sasl_passwd file with your Gmail account credentials, generating the hash file, and restarting the Postfix service. By following these steps, you can establish a secure TLS connection with Gmail’s SMTP server and resolve the error.

Understanding the Error

Before we delve into the solution, it’s important to understand the error. The “Must issue a STARTTLS command first” error is thrown when the Postfix system attempts to send an email without initiating a STARTTLS command. STARTTLS is a way to take an existing insecure connection and upgrade it to a secure connection using SSL/TLS.

Configuring Postfix for TLS Encryption

To resolve this issue, you need to ensure that your Postfix configuration is correctly set up for TLS encryption. Here are the steps you can follow:

Step 1: Open the Postfix Configuration File

Open the main.cf configuration file for Postfix. This file contains all the configuration parameters for Postfix. You can open this file using any text editor. For example, if you’re using a Unix-based system, you can use the nano command:

nano /etc/postfix/main.cf

Step 2: Verify the Configuration Settings

Ensure that the following settings are present and correctly configured in the main.cf file:

relayhost = [smtp.gmail.com]:587
smtp_use_tls = yes
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_tls_security_level = encrypt
smtp_sasl_mechanism_filter = plain

Here’s what each of these parameters do:

  • relayhost: This parameter specifies the mail server to which Postfix will relay outgoing mail. In this case, it’s Gmail’s SMTP server.
  • smtp_use_tls: This parameter, when set to ‘yes’, tells Postfix to use TLS encryption when talking to the relay host.
  • smtp_sasl_auth_enable: This parameter, when set to ‘yes’, enables SASL authentication.
  • smtp_sasl_password_maps: This parameter specifies the lookup table for SMTP server authentication.
  • smtp_sasl_security_options: This parameter is used to control the SASL authentication methods that Postfix can use.
  • smtp_tls_security_level: This parameter controls the usage of TLS encryption for SMTP client and server sessions.
  • smtp_sasl_mechanism_filter: This parameter specifies the SASL mechanism to use for authentication.

Step 3: Create a sasl_passwd File

You need to create a sasl_passwd file in the /etc/postfix directory. This file should contain your Gmail account credentials in the following format:

[smtp.gmail.com]:587 yourusername@gmail.com:yourpassword

Remember to replace yourusername@gmail.com and yourpassword with your actual Gmail account credentials.

Step 4: Generate the Hash File

Run the postmap command to generate the hash file for sasl_passwd:

postmap /etc/postfix/sasl_passwd

This command will create a sasl_passwd.db file which Postfix uses for fast lookup of the SMTP server and credentials.

Step 5: Restart the Postfix Service

Finally, restart the Postfix service to apply the changes:

sudo systemctl restart postfix

Conclusion

After following these steps, Postfix should be able to establish a secure TLS connection with Gmail’s SMTP server, and the “Must issue a STARTTLS command first” error should no longer occur. Remember, it’s always important to secure your email servers to prevent any potential security breaches.

For more information and troubleshooting tips, you can refer to the official Postfix documentation or the Gmail SMTP settings guide.

What is Postfix?

Postfix is an open-source mail transfer agent (MTA) that is commonly used as an email server. It is known for its security, reliability, and ease of configuration.

Why am I getting the “Must issue a STARTTLS command first” error?

This error occurs when Postfix is unable to establish a secure TLS connection with the SMTP server. It typically happens when the necessary configuration settings for TLS encryption are not correctly set up in the Postfix configuration file.

How do I fix the “Must issue a STARTTLS command first” error in Postfix?

To fix this error, you need to ensure that your Postfix configuration is correctly set up for TLS encryption. This involves verifying and configuring specific parameters in the main.cf file, creating a sasl_passwd file with your Gmail account credentials, generating a hash file for sasl_passwd, and restarting the Postfix service.

What is STARTTLS?

STARTTLS is a command used to initiate a secure TLS connection over an existing insecure connection. It is commonly used to upgrade the connection between email servers from an unencrypted transmission to an encrypted one using SSL/TLS.

Can I use Postfix with Gmail as a relay?

Yes, you can use Postfix with Gmail as a relay to send outgoing emails. By properly configuring Postfix and setting up TLS encryption, you can relay your emails through Gmail’s SMTP server, which provides a secure and reliable email relay service.

Are there any additional resources for troubleshooting Postfix and Gmail relay issues?

Yes, you can refer to the official Postfix documentation or the Gmail SMTP settings guide for more information and troubleshooting tips. These resources provide detailed explanations and solutions for various Postfix and Gmail relay-related issues.

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