SMTP Connectivity

If you are private hosting Turbo360 and wish to use the SMTP connectivity to send email notifications then there are a few different parameters to consider depending on how your Turbo360 environment has been configured.

The key parameters which affect the configuration are:

• Visibility of SMTP server

  • Your SMTP service is public (eg SendGrid, Office365)

  • Your SMTP service is private (eg: Exchange Server within your network)

• Network integration of Turbo360 Function Apps / Web App

  • Your App Service is not VNET integrated

  • Your App Service is VNET integrated but you are using default routing

  • Your App Service is VNET integrated but you are forcing all traffic via the VNET

In the below table we summarize these options and there is more info about the configuration of each option below the table.

Option 1

Parameters:

• SMTP visibility = Public

• App Service VNET Integration = No

Required configuration

• Configure the SMTP allow list to cover the outbound IP addresses for the Web App and Processor Function App (see below commands to get ip addresses)

Considerations:

• Port 25 will not work in this scenario as Azure limits it

  • Use Port 587

• In this scenario there is going to be quite a few IP addresses to consider

The below Az CLI commands will get the IP address list

az webapp show -g <rg> -n <app> --query outboundIpAddresses -o tsv

az webapp show -g <rg> -n <app> --query possibleOutboundIpAddresses -o tsv

az functionapp show -g <rg> -n <app> --query outboundIpAddresses -o tsv

az functionapp show -g <rg> -n <app> --query possibleOutboundIpAddresses -o tsv

Option 2

Parameters:

• SMTP visibility = Public

• App Service VNET Integration = Yes

• VNET Routing = Default

Required configuration

• Configure the SMTP allow list to cover the outbound IP addresses for the Web App and Processor Function App (see below commands to get ip addresses)

Considerations:

• Although Port 587 is recommended, Port 25 should work in this scenario

• In this scenario there is going to be quite a few IP addresses to consider

Option 3

Parameters:

• SMTP visibility = Public

• App Service VNET Integration = Yes

• VNET Routing = All Traffic to VNET

Required configuration

• Configure the SMTP allow list to cover the address range of the device which controls outbound traffic from your VNET to public resources.  For many customers you may have a VNET Gateway or Firewall which traffic is routed through and the IP address range for this traffic is what you would configure.

Considerations:

• Although Port 587 is recommended, Port 25 should work in this scenario

Option 4

Parameters:

• SMTP visibility = Private

• App Service VNET Integration = Yes

• VNET Routing = All Traffic to VNET

Required configuration

• Configure the SMTP allow list to cover the address range of the subnet which the App Service traffic is flowing into for the Web App and Processor Function App

Considerations:

• Although Port 587 is recommended, Port 25 should work in this scenario

Other Considerations

• I am using an App Service Environment V3

In this case you fall into the same scenario as option 2 or 3 depending on the parameters at the start of this page.  It just depends how you have configured your routing for the VNET integration.

Troubleshooting

🌐Use Network Troubleshooter in Azure Portal

If your app is VNet-integrated, go to:

App Service → Networking → VNet Integration → Network Troubleshooter

Then:

• Select Destination Type = FQDN or IP

• Enter your SMTP server and port (e.g. smtp.yourserver.com:587)

• It will trace from your App Service subnet and tell you if routing, DNS, or NSGs block it.

More Info

• https://learn.microsoft.com/en-us/azure/virtual-network/troubleshoot-outbound-smtp-connectivity