Send & Receive Issues

How to Fix Microsoft 365 Trial Email Error 550 5.7.708 Access Denied

Chanuka Geekiyanage Sep 25, 2026 869 views

Question details

The user is unable to send emails during a Microsoft 365 trial due to an Access Denied error.

How to Fix Microsoft 365 Trial Email Error 550 5.7.708 Access Denied

Product: Microsoft 365
Device & OS: not provided
Scenario: Attempting to send outbound emails using a newly created Microsoft 365 trial account.
Observed behavior: Outbound emails are rejected and bounce back with a Non-Delivery Report containing error code 550 5.7.708, indicating the sending IP address is blocked.

Before you start

Locate the Non-Delivery Report (NDR) in your inbox and copy the message headers, as you will need the specific blocked IP address to submit a delisting request.

Solution 1Recommended

Submit an IP Delisting Request to Microsoft

Check if your sending IP address is on the Microsoft 365 blocked senders list and request its removal.

Error 550 5.7.708 frequently occurs in trial tenants because Microsoft restricts outbound mail from known low-reputation IP addresses to prevent spam.

Using the official delisting portal will verify your IP status and initiate the unblocking process across Microsoft's email servers.

Identify the blocked IP

Open the bounced email (Non-Delivery Report) and locate the section detailing the sending IP address that was rejected.

Access the Delist Portal

Navigate to the Microsoft 365 Anti-Spam IP Delist Portal in your web browser.

Submit your information

Enter the blocked IP address and an email address where Microsoft can contact you, then complete the CAPTCHA and click Submit.

Confirm your request

Check your inbox for a confirmation email from Microsoft, click the provided confirmation link, and wait for the delisting process to complete.

Submit an IP Delisting Request to Microsoft

Processing Time: Once your delisting request is accepted, it may take up to 24 hours for the change to propagate globally and allow you to send emails.

Solution 2

Contact Microsoft 365 Support with Tenant Details

If the delisting portal does not resolve the issue, open a private support ticket to investigate tenant-wide restrictions.

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Frequently Asked Questions

Why am I getting Error 550 5.7.708 on my new Microsoft 365 trial?

Microsoft automatically places restrictions on newly created trial tenants to prevent spammers from exploiting their services. Error 550 5.7.708 indicates that the sending IP assigned to your trial account has been flagged and blocked.

How long does it take for a Microsoft IP delisting request to work?

Although the automated system may process your request within a few hours, it can take up to 24 hours for the unblocking changes to fully synchronize across all Microsoft 365 servers worldwide.

Should I post my Non-Delivery Report (NDR) in public forums to get help faster?

No. Your Non-Delivery Report contains sensitive information, including internal network IP addresses and routing data. You should only share this information through private messages with official Microsoft support personnel.

Does Error 550 5.7.708 mean my account has been hacked?

Not necessarily. While it can occur if a compromised account sends spam, for new Microsoft 365 trial accounts, it is almost always a strict default anti-spam measure rather than a sign of a security breach.

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