Problem sending email from hotmail address

Question

I keep getting the error message: "Your message wasn't delivered because the recipient's email provider rejected it."

There is no rhyme or reason to it. I can't send ANY emails out all of a sudden at all and this is the message kicking back for all of them. Please help!

Answer 1

Hello, thank you for your reply.

Your email was flagged as spam by the recipient's system. Error code 550/554 5.7.520 ... identified as spam. AS(4810) means exactly that.

This usually happens when you send emails through Outlook and the recipient’s server flags the message as suspicious. Possible reasons include the type of attachment, the format of the email content, or the message being blocked as spam.

Make sure the body of the email does not contain spam-like phrases or too many links.

You can use online spam testing tools such as: https://glockapps.com/

Disclaimer: This is a non-Microsoft website. This page appears to provide accurate and safe information. Be wary of advertisements on the site, which may promote products frequently classified as PUPs (potentially hazardous). Carefully review any product advertisements on the site before deciding to download and install them.

These tools will tell you whether SPF, DKIM, and DMARC pass, and whether the subject line and content of your email are likely to be intercepted.

Answer 2

Hello,

Can you successfully send emails to other email addresses? Could you provide the complete bounce message so I can determine the specific reasons why the email was blocked?

Currently, you can try contacting the recipient and adding your email address to your list of safe senders to see if you can successfully send emails to them.

Answer 3

The error means the receiving mail system is refusing to accept messages from the Hotmail/Outlook.com account. Common causes and actions:

1. Verify the exact error text

• In the non‑delivery report (bounce message), look for any of these patterns:
  • “blocked” or “listed in” plus references to sites like “spamcop,” “dynablock,” “blackhole,” or “spamhaus”.
  • “mailbox full,” “user unknown,” “host unknown,” etc.
• This text indicates whether the problem is with the recipient’s address, their mailbox, or a block/blacklist.

2. If the error mentions “blocked”, “listed in”, or spam/blacklist services

• This indicates the recipient’s server believes the Outlook.com/Hotmail server or account is a spam source.
• Action: Contact the support team for the recipient’s email provider and request that the account or domain be unblocked.

3. If the error is “Mailbox full” or “Quota exceeded”

• The recipient’s mailbox is over its storage limit and cannot receive new mail.
• Action: If possible, contact the recipient by another method and ask them to clear space.

4. If the error is “Mailbox not found”, “Invalid mailbox”, “User unknown”, or “Mailbox unavailable”

• The address may be wrong, no longer exists, or has moved.
• Action: Double‑check the recipient address for typos and confirm with the recipient (via another channel) that the address is still valid.

5. If the error is “Host unknown” or “Domain lookup failed”

• The domain part of the recipient’s address (after the @) does not exist or cannot be resolved.
• Action: Confirm the domain name is correct and hasn’t changed.

6. If the error is “Message too large”

• The message (often because of attachments) exceeds the recipient server’s size limit.
• Action: Upload large files to OneDrive and send a sharing link instead of attaching them directly.

7. If the error is “No adequate servers”, “Can’t connect to remote server”, “Connection timed out”, or “message expired”

• This typically indicates a temporary problem on the recipient’s side.
• Action: Wait and try sending again later. If the error says the recipient’s provider will keep trying, no action is needed.

Because this is affecting all outgoing messages, focus first on the exact wording of the bounce. If it includes “blocked” or blacklist references, the most likely resolution is to contact the recipient’s provider support and request removal of the block.

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References:

• Sent email in Outlook.com comes back "delivery failed"