Exchange Connection Problems

How to Fix Gmail SMTP Error 550 5.7.708 with Exchange Online

John Wilson Oct 22, 2026 868 views

Question details

The user is unable to send outgoing mail via Gmail using a Microsoft Exchange account because the SMTP connection is rejected with error 550 5.7.708.

Product: Microsoft Exchange Online
Device & OS: not provided
Scenario: Sending emails through a Gmail client via an authenticated Microsoft Exchange SMTP connection.
Observed behavior: The outgoing mail fails with Exchange Online error 550 5.7.708, indicating that traffic from the sending IP address is not accepted.

Before you start

Verify whether your Exchange Online account is running on a Microsoft 365 trial tenant, as this is the most common trigger for IP reputation blocks.

Solution 1Recommended

Contact Microsoft 365 Support to Request an IP Exception

Error 5.7.708 is a server-side restriction indicating Microsoft has blocked the IP due to low reputation, commonly affecting trial tenants. Requesting an exception is the standard resolution.

Re-adding your SMTP settings in the Gmail client will not fix this issue because the block is enforced at the server level by Exchange Online. You must contact support to whitelist the tenant.

Access the Admin Center

Open a Support Request

Navigate to the 'Support' or 'Help & Support' panel on the bottom right of the admin dashboard and select 'New service request'.

Submit Exception Request

Describe the issue by stating you are receiving 'Error 550 5.7.708 Access denied, traffic not accepted from this IP' and ask the support agent to grant an exception for your tenant to restore mail flow.

Contact Microsoft 365 Support to Request an IP Exception

License Purchasing: If you are using a trial tenant, upgrading to paid Microsoft 365 licenses often removes this low-reputation IP restriction automatically after the tenant is fully provisioned.

Solution 2

Verify Authenticated SMTP is Enabled

Ensure that your Exchange Online account permits authenticated SMTP connections, which is required for third-party clients like Gmail to send emails.

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Frequently Asked Questions

What exactly does Exchange Online error 550 5.7.708 mean?

This error means that Microsoft Exchange Online has denied access and blocked outgoing mail from your IP address. It is a security measure often applied to Microsoft 365 trial tenants to prevent spam from low-reputation IP addresses.

Can I fix the 5.7.708 SMTP error by changing settings in my Gmail client?

No. Removing and re-adding your Microsoft Exchange account or tweaking SMTP settings in your Gmail client will not bypass a 550 5.7.708 error, as it is a server-side block imposed by Microsoft.

How long does it take for Microsoft Support to lift the 5.7.708 restriction?

Once you submit a support ticket via the Microsoft 365 Admin Center requesting an exception, it typically takes 24 to 48 hours for the support team to investigate and restore your outgoing mail flow.

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