// how to fix
Not sure what is wrong?How to fix email problems
Your test or scan found a problem? Find the matching guide below: what it means, why it matters, and how to fix it step by step.
Bounce 40
DNS 36
DMARC 33
Reputation 33
SPF 30
DKIM 27
Gmail 19
Security 19
Blacklist 18
Content 14
Headers 11
Mailing list 11
Spam score 11
Reverse DNS 10
Microsoft 365 8
Outlook 8
Mail server 7
MX 5
Yahoo 4
TLS 3
Apple 2
Google Workspace 2
BIMI 1
E-commerce 1
GMX 1
WordPress 1
Zoho 1
8 guides · tag Microsoft 365
| Problem | In short | Tags | |
|---|---|---|---|
| Your emails land in Outlook or Hotmail junk | Outlook.com, Hotmail and Live send many new senders to Junk. Check your setup, then use Microsoft's free sender tools: SNDS, JMRP and the delist portal. | Fix it | |
| Set up SPF, DKIM and DMARC for Microsoft 365 | A complete checklist to authenticate a domain that sends with Outlook in Microsoft 365: the SPF include, the two DKIM CNAME records, and a first DMARC record. | Fix it | |
| Microsoft 365 "550 5.1.8 Access denied, bad outbound sender" | Microsoft 365 has blocked a user from sending because the account sent spam, usually after being hacked. Secure the account, then unblock it. | Fix it | |
| DKIM with CNAME records: delegated selectors (Microsoft 365, SendGrid…) | Many providers ask for DKIM as CNAME records instead of a TXT key. Here is how they work and the mistakes that break them. | Fix it | |
| Microsoft 365 "550 5.7.606 Access denied, banned sending IP": how to delist your IP | Microsoft 365 rejects your email because your IP is on its banned list (5.7.606 to 5.7.649). Learn how to use the delist portal sender.office.com. | Fix it | |
| Microsoft "550 5.7.509 ... does not pass DMARC verification and has a DMARC policy of reject": how to fix it | Outlook and Microsoft 365 reject your email because it fails DMARC and your domain uses p=reject. Fix SPF or DKIM alignment to get delivered. | Fix it | |
| Microsoft 365 "554 5.2.0 STOREDRV.Submission.Exception:SendAsDeniedException": how to fix it | Microsoft 365 refused to send because the account has no Send As permission for the From address. Fix permissions in Outlook, apps, printers and scripts. | Fix it | |
| Microsoft 365 "550 5.4.1 Recipient address rejected: Access denied. AS(201806281)": what it means and how to fix it | Microsoft 365 rejected your email because the recipient address does not exist in that organization. Learn what senders and admins can do about 5.4.1. | Fix it |
Not sure what is wrong?
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