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This guide walks you through installing and configuring Postfix on an Azure VM to relay all outbound mail through MailChannels Outbound Filtering.
Azure blocks outbound port 25 on VMs. This guide uses port 2525, which MailChannels configures identically to port 25.

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Prerequisites

  • Root or sudo access to your Azure VM
  • Your MailChannels SMTP username and password

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Configure the relay

1

Install Postfix

Connect to your VM over SSH and install Postfix along with the SASL authentication modules. When prompted during installation, select Local Only as the configuration type.Debian/Ubuntu:
RHEL/CentOS:
2

Configure main.cf

Open /etc/postfix/main.cf in a text editor. Find and comment out the following lines if present:
/etc/postfix/main.cf
Then append the following configuration to the end of the file:
/etc/postfix/main.cf
3

Create the password file

Create /etc/postfix/password with your MailChannels SMTP credentials. The file is space-delimited — do not use tabs:
/etc/postfix/password
Secure the file and generate the Postfix hash map:
4

Restart Postfix

Debian/Ubuntu:
RHEL/CentOS:

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Verify the configuration

1

Send a test email

Install a mail utility and send a test message to an address you control.Debian/Ubuntu:
RHEL/CentOS:
Then send the test:
2

Check the mail log

Tail the mail log to confirm the message was accepted and cleared from the queue without errors:
3

Review the MailChannels Host Console

Log in to your MailChannels Host Console and check Outbound > Activity > Log Search to confirm your test message was processed and delivered.