Full diagnosis
Review of DNS, the mail server and the sending logs, plus real tests with several providers.
Email · Deliverability
Emails going to spam: diagnosis and fix
If your customers are not getting your invoices or quotes, or Gmail and Outlook send you to the spam folder, there is almost always a specific technical cause. I find it and fix it.
Common causes
What I usually find when emails do not arrive.
- An SPF record that does not include every service sending on your behalf (the website, the shop, the CRM…).
- No DKIM signature, or a published key that does not match the server’s.
- No DMARC policy, or one that does not fit how you send.
- The server’s IP on a blocklist because of an abused form or a compromised website.
- Generic reverse DNS (PTR) or one that does not match the server name.
- Email sent from the same server that hosts vulnerable websites.
What I do
Whether you have your own mail server or use Google Workspace or Microsoft 365.
Authentication
SPF, DKIM and DMARC configured and checked, including emails sent by the website or shop.
Blocklists
First remove the cause, then request delisting from Spamhaus and the other lists.
Mail server
A well-configured Postfix, with authenticated sending, brute-force protection and no open relay.
How I fix it
Measure first, then fix, then measure again.
- 1
Measure
Test sends and header review to see exactly what is failing.
- 2
Fix
DNS, server and, if needed, the website or form causing it.
- 3
Clean up reputation
Delisting once the cause has been removed.
- 4
Verify
New tests until delivery is right.
Technologies
Frequently asked questions
What are SPF, DKIM and DMARC?
SPF says which servers can send email on behalf of your domain; DKIM signs each message to prove it has not been altered; and DMARC says what to do with emails that fail those checks. Gmail and Outlook increasingly require them.
How long does it take to get off a blocklist?
Once the cause is removed, many lists delist the IP within hours or a few days. Some do it automatically and others require a request.
I use Google Workspace or Microsoft 365, does this affect me?
Yes. Even if Google or Microsoft handle your email, your domain’s SPF, DKIM and DMARC still need configuring, and if your website also sends emails it has to be included.
Why do my emails reach some people but not others?
Each provider applies its own filters and its own reputation. That is why tests are run with several at once, not just one.
You may also be interested in
Contact
Let's talk
Got an idea to build, a platform that has fallen short or a network that keeps scaring you? Tell me. I will tell you how I would do it, how long it would take and what it would cost, with no commitment.
Or email me directly: