All emails I send out are being rejected as it contains spam

Question

I was blocking and then deleting spam emails but unfortunately one of them had my email address as part of their address. Now when I send an email they are being rejected as it contains spam how do I rectify this

Answer 1

Hello

Have you unblocked your email address first?

To do so, go to https://www.outlook.com > Settings > Mail > Junk, remove yourself from the block list.

Then try to see if that helps with outbound emails.

If not, Can you use the instruction here, change the email to plain text or rich text format (basically avoid the html format) and see if it goes through:

https://support.microsoft.com/office/change-the-message-format-to-html-rich-text-format-or-plain-text-in-outlook-338a389d-11da-47fe-b693-cf41f792fefa

Answer 2

All outbound mail is being rejected because the address or sending account is now treated as a spam source by one or more mail systems. Fixing this has two parts:

1. Remove any self‑blocking or junk settings in Outlook.com.
2. Address any server‑side or provider‑side spam/block issues shown in the non‑delivery reports (NDRs).

Below are concrete steps tailored to Outlook.com / Outlook on the web.

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1. Check the exact error in the bounce message

Open one of the “delivery failed” messages and look for:

• Status codes like 550, 553, or text such as:
  • 550 5.1.8 Access denied, bad outbound sender
  • “blocked”, “listed in”, or references to blacklist sites (spamhaus, spamcop, etc.)

This tells whether the problem is:

• The own account being blocked as a bad outbound sender, or
• The recipient’s server blocking the mail as spam.

Use the matching section below based on what is seen.

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2. If the bounce shows 550 5.1.8 Access denied, bad outbound sender

This means the account has exceeded sending limits or was flagged as a spam source in Exchange Online.

If this is a work/school (Microsoft 365) account:

Ask the email administrator to do all of the following:

1. Check whether the account is compromised
   Follow the guidance in Secure a compromised email account in Exchange Online:
   • Reset the user’s password.
   • Review and remove any malicious inbox rules or forwarding.
   • Check sign‑in logs for suspicious activity.
2. Unblock the account in Microsoft 365 Defender
   • Go to the Microsoft 365 Defender portal → Restricted entities page (https://security.microsoft.com/restrictedusers).
   • Locate the affected user account in the list.
   • Select it and choose the option to Unblock.
   • After unblocking, sending restrictions are usually removed within about one hour.
3. Harden the environment
   To reduce the chance of this happening again, follow the recommendations in Top 10 ways to secure your business data (multi‑factor auth, strong passwords, etc.).

This flow is described in detail in the “550 5.1.8 Access denied, bad outbound sender” guidance.

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3. If the bounce mentions “blocked” / “listed in” (spamhaus, spamcop, etc.)

In this case, the recipient’s email provider is blocking the server or domain as a spam source.

Steps to take:

1. Confirm the error text
   Look for wording like:
   • “blocked” or “listed in”
   • References to blacklist providers (e.g., spamhaus, spamcop, dynablock, blackhole).
2. Contact the recipient’s provider
   As described in the Outlook.com delivery‑failure guidance:
   • Use the support channel of the recipient’s email provider.
   • Provide them with the full error text from the NDR.
   • Request that the sending account or domain be unblocked.
3. Ask the recipient to whitelist the address
   The recipient can add the address to their safe senders/allow list to help ensure delivery once the block is lifted.

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4. Fix self‑blocking and junk settings in Outlook.com

Because a spam message contained the own address in the From or address string, it is possible that the address or domain was accidentally added to the Blocked senders and domains list.

To correct this in Outlook.com / Outlook on the web:

1. Open Outlook.com and sign in.
2. Select Settings (gear icon) at the top.
3. Select Mail → Junk email.
4. Under Blocked senders and domains:
   • Look for the own email address.
   • If it appears, select it and remove it from the list.
5. Select Save.

This ensures Outlook.com itself is not treating the own address as junk.

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5. Reset junk‑mail handling if spam logic seems “stuck”

If junk handling or spam classification seems wrong (for example, legitimate mail is treated as spam or spam logic is behaving oddly), a reset of junk handling in Outlook.com has been reported to help:

1. In Outlook.com, go to Settings → Email → Junk Email.
2. Set Incoming mail handling to Strict.
3. Select Save.
4. Sign out of Outlook.com.
5. Sign back in.
6. Return to Settings → Email → Junk Email and set Incoming mail handling back to Standard.
7. Select Save.

According to user reports, after a few hours this reset can restore normal junk‑mail behavior. Do not expect immediate changes; allow some time for the change to propagate.

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6. If messages appear sent but never arrive (no bounce)

Some providers silently drop messages they consider spam. In that case:

1. Ask recipients to check their Junk/Spam folders.
2. Ask recipients to add the address to their safe senders list.
3. If the recipient’s provider is blocking silently, they must adjust their filters or unblock the sending server/domain.

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7. Summary of what to do now

1. Open a recent “delivery failed” message and identify the exact error text.
2. In Outlook.com, go to Settings → Mail → Junk email and remove the own address/domain from Blocked senders and domains if present.
3. If the NDR shows 550 5.1.8 Access denied, bad outbound sender and this is a work/school account:
   • Have the admin secure the account and unblock it on the Restricted entities page in Microsoft 365 Defender.
4. If the NDR mentions “blocked” or “listed in” with blacklist names:
   • Contact the recipient’s email provider support and request unblocking of the account or domain.
5. Optionally reset junk handling (Strict → sign out/in → Standard) and wait a few hours.

Once the block/unblock actions and junk‑filter corrections are completed and have had time to propagate, new messages should start delivering normally.

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References:

• NDR error code "550 5.1.8 Access denied, bad outbound sender"
• Sent email in Outlook.com comes back "delivery failed"
• Filter junk email and spam in Outlook
• Outlook.com doesn't send any emails to junk folder - Microsoft Q&A