Microsoft (Outlook.com and Microsoft 365) · permanent error
5.7.507: sending IP blocked by the recipient organization
The recipient's organization has blocked the IP address you send from; only the recipient can lift the block.
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At a glance
- Code
- 5.7.507
- Temporary or permanent
- PermanentRefused for good: the message comes back to the sender, and resending it gets the same answer.
- Who has to act
- The recipient's side. Their mail admin has to change something; you can tell them.
- What the server says
5.7.507 Access denied, rejected by recipient
What it means
5.7.507 means the block was set by the recipient's organization: it has blocked the IP address you are sending from. Microsoft's guidance is simply to contact the recipient, because the decision is theirs. Microsoft's own delisting routes, the delist portal and delist@microsoft.com, are for blocks Microsoft places, so they do not apply here. Reach the recipient by some other channel and ask them to have their admin remove the block.
Common causes
- The recipient organization blocked your sending IP, perhaps after unwanted mail from it.
- You share a sending IP with another sender the recipient chose to block.
How to fix it
- 01Contact the recipient by phone or another channel and ask them to have the block removed.
- 02Give them the IP address from the bounce and the time of the attempt.
- 03If you use a shared IP from an email provider, ask the provider about a different IP.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- Email nondelivery reports and SMTP errors in Exchange Onlinelearn.microsoft.com
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