Azure VM as SMTP Relay

Question

Does Microsoft support using an Azure VM as an SMTP Relay server? For example, an on-premises application that does not support sending authenticated emails sending the emails to an Azure VM/Mail relay server, which then passes the email to a 3rd party provider (SendGrid, Mailchimp, etc.) as authenticated?

If the emails are sent over TLS (587) would Microsoft throttle or block the traffic?

Answer 1

Hi @Steven Couture ,

Configure an SMTP in Azure like this :

http://woshub.com/how-to-install-and-configure-smtp-server-on-windows-server-2012-r2/

Will work.

Don’t forget to open port 25 or 587 if you use NSG or firewall.

What is important when you want to do mass mailing is configuration of dkim, spf ….

You can use Exchange online mailbox too with smtp server.

Hope it helps.

Answer 2

Hi @Steven Couture ,

VMs running a SMTP server is only available only in some Azure subscription types.

Please take a look here:
https://learn.microsoft.com/en-us/azure/virtual-network/troubleshoot-outbound-smtp-connectivity

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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)

Regards
Andreas Baumgarten

Answer 3

We found that doing the following worked, and can now edit the settings in the II6 Manager without errors (and without crashing when applying settings) every time:

1. Stop SMTPSVC service [Display Name: Simple Mail Transfer Protocol (SMTP)]
2. Stop IISADMIN service [Display name: IIS Admin Service]
3. Edit "C:\Windows\System32\inetsrv\MetaBase.xml"
4. Find: <IIsSmtpServer Location ="/LM/SmtpSvc/1"
5. Add (Settings are alphabetical): RelayIpList=""
6. Save file
7. Start IISAdmin Service
8. Start SMTPSVC service

You can now open the Internet Information Services (IIS) 6.0 Manager (InetMgr6.exe) and work like normal. The setting above relates to the Access Tab > Relay Restrictions section, but doesn't set anything in it (i.e. "all except the below list" with a blank list).

After setting this value you can change it to what you need it to be. (i.e. the value doesn't need to be 'null' for the fix to work, just so long as the variable is present in the file).

The above has been tested on a few new installs of Windows Server 2022, and has worked for us every time. If you have done an upgrade there are some other things to consider (seems like the SMTP service is not installed after upgrade so will require a backup of the settings that can be applied post reinstalling the service. But that is discussed in other topics).

PS: Remember to set the SMTPSVC service to start "automatically". By default its set to "manual".

Source: https://serverfault.com/questions/1088555/server-2022-smtp-server-issue