Why your email goes to spam, and how to fix it
If your mail lands in spam, the cause is almost always that the receiving server cannot confirm you are allowed to send as your domain. Three DNS records fix that.
Check first, then change
Send a message from the affected address to one of the free mail-testing services, which reply with a report on your SPF, DKIM and DMARC. Do this before editing anything, so you know which one is actually wrong.
SPF - who may send as you
A TXT record on the root domain listing every server permitted to send. It must include all of them: your mail host, your website (contact forms and order confirmations), your invoicing tool, your newsletter service.
Two rules that catch people out: there must be exactly one SPF record - a second one invalidates both - and it may not exceed ten DNS lookups, so a record with five include: entries can silently break.
DKIM - a signature on each message
Enable it in cPanel under Email Deliverability; it publishes the key for you. If your domain uses another provider's nameservers, cPanel will show you the record to copy across manually - and it is long, so copy it as one line with no inserted breaks.
DMARC - what to do when the first two fail
A TXT record at _dmarc.yourdomain.com. Start with v=DMARC1; p=none; rua=mailto:you@yourdomain.com and read the reports for a fortnight. You will find systems sending as you that you had forgotten. Once they are all in SPF, move to p=quarantine, then p=reject.
Going straight to reject is how a company stops receiving its own order confirmations.
If all three are correct and it still happens
- Check your IP is not listed. A blacklist lookup will say. If it is, find what was sending - usually a compromised contact form.
- Look at the content. A message that is one big image, or full of urgent capitals and shortened links, scores badly whatever your DNS says.
- Warm a new domain slowly. A brand-new domain sending three hundred messages on its first day looks exactly like a spammer, because that is what spammers do.
- Use a proper sending service for bulk mail. Newsletters should not go through your mailbox; one complaint rate affects the other.