Your emails are not received at all: a step-by-step checklist

What it means

You send an email, it leaves your mailbox, but the recipient never sees it. It can be lost at three places: on your side (it never really left), on the way (the receiving server refused it) or at the recipient (it was filtered, quarantined or deleted).

Working through the checks below in order usually finds the cause in a few minutes.

Why it matters

A silent problem is the worst kind: invoices, quotes and password resets disappear and nobody knows. One bad setting can block every email you send to a whole provider.

The checklist

1. Look for a bounce. Search your inbox for a message from "Mail Delivery Subsystem", "Postmaster" or "MAILER-DAEMON". It contains a code and a reason. A code starting with 5 (like 550) is a permanent refusal; a code starting with 4 is temporary and the server keeps retrying.
2. Check that it was really sent. Is the email in your Sent folder, or stuck in the Outbox? Did your provider show a warning such as "sending limit reached" or "account suspended"?
3. Check the address. One wrong letter is enough. Also check that the recipient's domain can receive email: type it at /domain-scanner and look for MX records.
4. Ask the recipient to check spam, junk and quarantine. In companies using Microsoft 365 or other filters, emails can be held in a quarantine that only the IT team sees. Also ask them to check their blocked senders list and inbox rules.
5. Send a test to Delivmail. On the home page, copy your unique test address and send it a normal email from the same mailbox. If nothing arrives within a few minutes, the problem is on your side: sending settings, account or provider.
6. Read the report. If the test arrives, look at the red items first:
   • SPF, DKIM or DMARC failing.
   • Your IP address or domain on a high-impact blacklist.
   • No reverse DNS on your own server.
   • A high spam score.
   Each problem has its own guide.
7. Use your provider's message trace. Microsoft 365 has "Message trace" in the Exchange admin center, Google Workspace has "Email log search" in the Admin console. They show whether the email was delivered, deferred or refused, and why.

Common causes

• A missing or broken SPF record after changing provider.
• DMARC set to p=reject while DKIM is not working.
• Your own server's IP listed on Spamhaus.
• A website or app sending from a server that is not in your SPF.
• The recipient's company filter blocking your domain.

Tips

• Keep the full bounce message: the error text often names the exact problem and a help link.
• Test with addresses at several providers (Gmail, Outlook, Yahoo) to see if only one is affected.
• If only one recipient is affected, the problem is probably on their side.

Check that it is fixed

After each fix, send a new test email from the home page and check that the report is green. Then send a real email to the person who reported the problem and ask them to confirm it arrived in the inbox.