fail to send email

Question

fail to send email

Datalink 0

I have small python to test email.

With this code, if I use on my pc I can send email.

Is use this server (production server on near future, testing email for now) and does not work.

It's not firewall problem, because I can telnet to smtp.office365.com 587.

When I go to mailbox, I see that email failed to send due to this message in below.

Diagnostic information for administrators:

Generating server: DU0P251MB1009.EURP251.PROD.OUTLOOK.COM

******@epsmail.eu Remote server returned '550 5.7.708 Service unavailable. Access denied, traffic not accepted from this IP. For more information please go to http://go.microsoft.com/fwlink/?LinkId=526653 AS(8561) [DB9P251MB0220.EURP251.PROD.OUTLOOK.COM 2025-01-29T18:35:19.953Z 08DD3E67A7FFDF7A]'

Original message headers:

Received: from DU0P251MB1009.EURP251.PROD.OUTLOOK.COM
 ([fe80::9b0f:aaaf:6c4d:94]) by DU0P251MB1009.EURP251.PROD.OUTLOOK.COM
 ([fe80::9b0f:aaaf:6c4d:94%4]) with mapi id 15.20.8398.017; Wed, 29 Jan 2025
 18:35:20 +0000
MIME-Version: 1.0
Content-Type: text/plain
Date: Wed, 29 Jan 2025 18:35:20 +0000
Message-ID:
 <******@DU0P251MB1009.EURP251.PROD.OUTLOOK.COM>
Subject: Test Email

1 answer

Your answer

Answer 1

Jake Zhang-MSFT 9,095 Microsoft External Staff

Hi @Datalink ,

Welcome to the Microsoft Q&A platform!

Based on your description, it looks like your IP address has been blocked by Office 365, which is causing emails to fail with the error message "550 5.7.708 Service Unavailable. Access Denied, Not Accepting Traffic from This IP". This can happen if the IP address is flagged for sending spam or other suspicious activity.

Here are some steps you can take to fix this:

Use the Office 365 Delisting Portal to see if your IP address is listed, and if so, request it be removed.
If delisting the IP doesn't fix the issue, you may want to create a service request in the Office 365 Admin Center. They can provide more detailed assistance and help ensure your IP is not blocked.
Make sure your emails comply with Office 365 policies to avoid being flagged in the future. This includes avoiding sending large volumes of emails in a short period of time and making sure your emails are not marked as spam.

Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang

Datalink 0 Reputation points

2025-01-30T16:30:54.88+00:00

I'm not sure if I understand correctly. Are you saying that the recipient (Office 365) should delist the IP address of the sender (origin)?

The issue is that I can't send emails to anyone(outlook, gmail, zoho). The sending server is hosted on AWS, and so far, I've only sent around 10 to 15 emails in total—too few to be classified as spam.

Why can I send emails from my personal pc but not from the AWS server? The mail account is the same.

I can't ask every recipient to delist the IP address...
Jake Zhang-MSFT 9,095 Reputation points Microsoft External Staff

2025-01-31T07:57:58.58+00:00
Hi @Datalink ,

The issue seems to be related to the IP address of your AWS server being blocked or flagged, which is different from your personal PC's IP address. Here are some steps to help resolve this:

AWS often restricts outbound traffic on port 25 by default. Make sure you have requested the removal of this restriction if you're using port 25. Alternatively, use ports 587 or 465, which are typically not restricted.

Ensure your AWS server has an Elastic IP address assigned to it. This helps maintain a consistent IP address, which is important for email reputation.

Set up reverse DNS for your Elastic IP address and ensure you have proper SPF and DKIM records configured. This helps prevent your emails from being flagged as spam.

Consider using Amazon Simple Email Service (SES) for sending emails. SES is designed for high deliverability and can help avoid issues with IP reputation.

Office 365 has strict policies for incoming emails to prevent spam. Ensure your emails comply with these policies, including proper authentication and avoiding spam-like content.
Jake Zhang-MSFT 9,095 Reputation points Microsoft External Staff

2025-02-05T01:29:15.75+00:00

Hi @Datalink ,

Please kindly consider this comment as a warm follow up, I want to know if your problem has been solved. If you still have any other questions, please feel free to comment here and I'm glad to provide further support.If the above info is helpful to this question, you can click "Accept Answer". Have a nice day!

Best,

Jake Zhang

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