From Azure VM dot net application is hosted. I could not send email from the application

NewCoder 0

In azure VM dot net application has been hosted. Through application we are sending emails. It was working fine till last week once the azure subscription got deactivated and reactivated all the settings gone. Now mails are in Queue directory.

We are using godaddy SMTP relay.

In webconfig, we added below. <system.net>

    <mailSettings>

        <smtp deliveryMethod="Network">

            <specifiedPickupDirectory pickupDirectoryLocation="C:\inetpub\mailroot\Pickup" />

            <network host="XX.XX.XX.XX" port="25" />

        </smtp>

    </mailSettings>

</system.net>

In IIS, for the the SMTP of the domain application as below.

All the above settings used to work before.

Now all the emails are in Queue of mailroot.
Another important thing is between the VMs only internal IP sharing is happening not with VMs name sharing.
For example VM1 and VM2. VM1 as shared directory of DATA. Previously it used share if we give VM1\Data from VM2. But now its not working we have to use 10.0.0.1\DATA

NewCoder 0 Reputation points

2024-11-16T17:18:20.26+00:00

When I do connection troubleshoot through azure portal above is the error. How to resolve DNSResolution.

1 answer

Marcin Policht 26,310 Reputation points MVP

2024-11-16T16:45:33.3866667+00:00

SMTP outbound is blocked by default.

Follow https://zcusa.951200.xyz/en-us/azure/virtual-network/troubleshoot-outbound-smtp-connectivity

If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

hth

Marcin
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NewCoder 0 Reputation points

2024-11-16T17:29:05.8233333+00:00

Hi Marcin,

Thank you fro the reply.

Local Error DNS Resolution it says when I do connection trouble shoot from Azure VM to smtp email server. At azure VM port 25 is open from firewall.

Marcin Policht 26,310 Reputation points MVP

2024-11-16T17:42:14.03+00:00

Blocking applies on the platform level - this is not a VM setting.

You'd want to apply the following recommendation from the article I referenced earlier:

Recommended method of sending email

We recommend you use authenticated SMTP relay services to send email from Azure VMs or from Azure App Service. Connections to authenticated SMTP relay services are typically on TCP port 587 which is not blocked. These services are used in part to maintain IP reputation which is critical for delivery reliability. Azure Communication Services offers an authenticated SMTP relay service. Ensure that the default rate limits are appropriate for your application and open a support case to raise them if needed.

Using these email delivery services on authenticated SMTP port 587 isn't restricted in Azure, regardless of the subscription type.

If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

hth

Marcin
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