Mail from Hospital domain Exchange server ip: [Moderator note: personal info removed] is blocked

Question

Exchange Online Protection (EOP) service within Office 365 is blocking outgoing mail from Exchange server of Hospital with external IP [Moderator note: personal info removed].

Please unblock and remove this IP from spam filtering..

Thanx

Answer 1

Please note that Q&A forum is a public platform, and moderators will modify the question to hide personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.

Hello Istok Ferjan,

Thank you for reaching out to Microsoft Q&A. I'm sorry to hear you're experiencing issues with outbound email from your hospital's being blocked. This is often due to detected suspicious activity, such as potential spam, but it can usually be addressed through Microsoft's self-service delisting process. As the IP appears to be on an internal block list, as a forum moderator, I can't unblock it directly. Microsoft's security policies require the request to come from an authorized party via the official portal to prevent abuse. As Q&A assist has mention, you can go to the Office 365 Anti-Spam IP Delist Portal at https://sender.office.com. Microsoft typically reviews these within a few hours, but approval depends on no ongoing issues like malware or policy violations. If approved, the block should lift shortly after.

Alternative, you could ask the recipient to Whitelist Your IP:

If the block is only affecting one organization (or a few):

Ask their Microsoft 365 admin to add your IP to their IP Allow List:

Microsoft Defender portal → Policies & rules → Threat policies → Anti-spam policies → Connection filter policy (default) → Edit → IP Allow List → add the IP.

This skips EOP filtering for mail from your server to that tenant only.

Hope this help.

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Answer 2

If the Exchange server with the external IP [Moderator note: personal info removed] is being blocked by Exchange Online Protection (EOP), you can request the removal of this IP from the blocked senders list using the Office 365 Anti-Spam IP Delist Portal. Here are the steps you should follow:

1. Go to the Office 365 Anti-Spam IP Delist Portal at https://sender.office.com.
2. Enter the email address that received the non-delivery report (NDR) and the specified IP address ([Moderator note: personal info removed]).
3. Follow the instructions on the portal and submit your request.
4. You will receive a confirmation email with a link to return to the delist portal.
5. In the delist portal, select Delist IP.

Please note that it may take up to 24 hours or longer for the restrictions to be removed after your request is processed. Additionally, ensure that your emails comply with Microsoft’s security features to avoid being blocked again.

If you encounter a specific error code like 5.7.511, you may need to follow different procedures as the delist portal won't work for that case.

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References:

• External senders - Use the delist portal to remove yourself from the blocked senders list and address 5.7.511 Access denied errors
• External senders - Troubleshoot email sent to Microsoft 365