// how to fix
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.
DNS 33
DMARC 28
SPF 28
DKIM 26
Reputation 24
Bounce 16
Security 16
Blacklist 13
Gmail 13
Content 12
Mailing list 11
Spam score 10
Headers 9
Reverse DNS 7
Mail server 4
Microsoft 365 4
MX 4
Outlook 4
TLS 2
Apple 1
BIMI 1
E-commerce 1
Google Workspace 1
WordPress 1
Yahoo 1
Zoho 1
4 guides · tag Outlook
| 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 | |
| Gmail shows "via" or "sent on behalf of" next to your name | Recipients see "via another-domain.com" or "on behalf of" because your email is signed or sent with another domain. Sign it with your own domain. | Fix it | |
| Outlook shows "?" or "We can't verify the sender" | Outlook replaces your photo with a question mark or says it cannot verify who sent the email. It means authentication failed; here is how to fix it. | Fix it | |
| Microsoft "451 4.7.500 Server busy": temporary deferral | Outlook.com and Hotmail are holding back emails from your IP because they do not know it or trust it yet. Keep volumes low and build reputation. | Fix it |
Not sure what is wrong?
Send a test email or scan your domain: the report tells you which problem you have.