I have built a solution using python flask and created the web app for that in azure. The solution will send smtp email using port 25 to GE emails. The solution is working fine in my IDE but, failing on azure as, it cant send email to GE outlook and throwing error of “[Errno -5] No address associated with hostname” Is the issue related to azure outbound restriction on smtp? if, yes then how can I lift up the restriction please, let me know and for what whom should I contact.

Hi, I guess, your email administrator can help on this. Here the relay request is coming form Azure which has a public IP. You can provide the IP to your email administrator. They can create the connector for this purpose. Note that, email systems can't authenticate from unknown sources. Here Azure email relay request is an unknown source and to be resolved Please mark as "Accept the answer" if the above steps helps you. Others with similar issues can also follow the solution as per your suggestion Regards, Manu

Hello, The mail server you use for relaying the emails should have an associated connector created with required permissions. The mail server you are trying to connect can't understand the mails you are initiating from azure. So, create the required connector and fix it Please mark as "Accept the answer" if the above steps helps you. Others with similar issues can also follow the solution as per your suggestion Regards, Manu

Unauthenticated outbound SMTP on port 25 is blocked in Azure. See: https://learn.microsoft.com/en-us/azure/virtual-network/troubleshoot-outbound-smtp-connectivity See the Pay as you Go section for how to remove the restriction or use a service that supports authenticated mail.

Outbound SMTP email issue

Accepted answer

Manu Philip 16,966 Reputation points MVP

2020-06-15T16:23:35.883+00:00

Hi,
I guess, your email administrator can help on this. Here the relay request is coming form Azure which has a public IP. You can provide the IP to your email administrator. They can create the connector for this purpose. Note that, email systems can't authenticate from unknown sources. Here Azure email relay request is an unknown source and to be resolved

Please mark as "Accept the answer" if the above steps helps you. Others with similar issues can also follow the solution as per your suggestion

Regards,

Manu
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MITRA, Debartha (GE CoreTech & Cyber) 51 Reputation points

2020-06-15T16:33:57.68+00:00

Thanks for your quick reply. If, you are mentioning about the ip of python flask app then, I already have made it publicly available by configuring the host ip to '0.0.0.0'. Are you mentioning about this ? which IP should I provide to my email administrator ?

Manu Philip 16,966 Reputation points MVP

2020-06-15T16:37:40.263+00:00

Hi,

I assume that you run the Python app in Azure Web application. The Web Application should have a public IP address so that the application can be accessed from outside world. You have to provide the same IP for relay request configuration

Thanks,
Manu

MITRA, Debartha (GE CoreTech & Cyber) 51 Reputation points

2020-06-15T17:06:37.227+00:00

Thank you, yes I have provided '0.0.0.0' ip in my flask app(Which means the app is publicly available). So, I should provide this ip to email admin right ? or anything else please, let me know.

Manu Philip 16,966 Reputation points MVP

2020-06-15T17:10:08.477+00:00

Hi,
P 0.0.0.0 can't work. You should have a valid public IP in my understanding

Thanks,
Manu

MITRA, Debartha (GE CoreTech & Cyber) 51 Reputation points

2020-06-15T17:41:19.03+00:00

OK, I can see in the azure portal (in custom domain section) that a particular ip is associated with my app service, so should I provide that ip to my email admin ?

Manu Philip 16,966 Reputation points MVP

2020-06-15T17:45:14.653+00:00

Yes, exactly. That IP should be allowed to be relayed through the email server

Thanks,
Manu

MITRA, Debartha (GE CoreTech & Cyber) 51 Reputation points

2020-06-15T17:48:33.787+00:00

Thank you for your reply, and also the Unauthenticated outbound SMTP on port 25 is blocked in Azure, so should I separately raise a request to lift up the restriction in auzre portal ?

Manu Philip 16,966 Reputation points MVP

2020-06-15T17:52:06.71+00:00

So far we were handling the issue of relaying the email from Azure App through your email server using your email address. If you have a requirement to receive emails in Azure application for some purpose, port 25 should be open. As suggested Andy David in a reply, you have to go for unblocking it

Thanks,
Manu

MITRA, Debartha (GE CoreTech & Cyber) 51 Reputation points

2020-06-15T18:02:20.523+00:00

No, my web application will only send mail through my company smtp server to my company email ids and I dont have requirement of receiving any email.
So, do I need to request to unblock then ?

Manu Philip 16,966 Reputation points MVP

2020-06-15T18:18:11.11+00:00

We need port 25 to be open for receiving emails

Thanks,
Manu

MITRA, Debartha (GE CoreTech & Cyber) 51 Reputation points

2020-06-15T18:22:58.173+00:00

ok, i will only send mail from my azure web application through my company email server using my company email address
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Outbound SMTP email issue

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