Run the free email record checker on your domain first. It takes under a minute and tells you which of the three records exist.
Confirm what is happening
Ask a customer who received a junked email to tell you which service they use (Gmail, Outlook, Yahoo or a company mail system) and whether it went to junk or never arrived at all. Junk and rejection are different problems. A message in junk was accepted and judged; a rejected message usually comes back to you as a bounce with a reason in it, which is worth keeping.
Then send a test from your business address to a personal Gmail or Outlook account. If it lands in junk there too, the problem is likely on your side and the records below are the place to start.
SPF: who is allowed to send as you
SPF is a TXT record on your domain listing the services allowed to send mail for it: your mailbox provider, and often your invoicing tool, newsletter service or website form. Mail from a service not on the list can fail the check.
The common faults: no SPF record at all; two SPF records, which is invalid and treated as an error; or a record that misses a service added later, such as a new booking system. A domain must have only one SPF record, so a new service is added to the existing record rather than given its own.
DKIM: a signature on every message
DKIM signs each outgoing message with a key, and publishes the matching public key in DNS under a name called a selector. A receiving service checks the signature against the key. A valid signature shows the message came from a sender authorised for the domain and was not altered on the way.
Each sending service needs its own DKIM set-up, usually two DNS records copied from that service’s settings. If your newsletter tool was never connected to your domain, its mail is signed for the tool’s own domain rather than yours. To find which selector your mail uses, open a sent message’s headers and read the s= value in the DKIM-Signature line; the email checker explains how in Gmail and Outlook, and checks a selector you enter.
DMARC: your instructions to inboxes
DMARC is a TXT record at _dmarc on your domain. It tells receiving services what to do with mail that claims to be from you but fails SPF and DKIM alignment (none, quarantine or reject), and where to send reports about it. Alignment means the domain that passed SPF or DKIM matches the domain in the From address your customer sees.
Start with p=none and a reporting address, read the reports for a few weeks to find every service sending as you, fix the ones that fail, then move to quarantine and reject. Going straight to reject without that step can block your own invoices.
The Gmail and Yahoo sender rules
In February 2024, Google and Yahoo began enforcing sender requirements. Google’s email sender guidelines require every sender to Gmail to use SPF or DKIM, have valid forward and reverse DNS for sending servers, use a secure connection and keep the rate of messages users report as spam low. Senders of close to 5,000 or more messages a day to personal Gmail accounts must also have SPF, DKIM and DMARC, with the From domain aligned, and offer one-click unsubscribe on marketing mail.
Google’s sender guidelines FAQ says enforcement on non-compliant traffic ramped up from November 2025, including temporary and permanent rejections. Yahoo’s sender best practices set similar expectations, including a one-click unsubscribe for marketing mail and a spam rate below 0.3%, and strongly urge every sending domain to publish DMARC.
Most small businesses send nowhere near 5,000 messages a day, but the authentication requirements apply to every sender, and a newsletter can push a domain’s volume up on the day it goes out.
Blocklists and sending reputation
If your records are in order and mail still goes to junk, check whether your sending server or domain appears on a blocklist. Spamhaus’s lookup covers the lists most widely used by receiving services. A listing on a shared server, common with cheap hosting that sends mail from the website’s own server, can affect every business on it.
Reputation also comes from behaviour: sending to old or bought lists, high bounce rates and recipients marking mail as spam all count against a domain. Google’s free Postmaster Tools shows the spam rate and reputation Gmail sees for your domain once you verify it, although it needs a meaningful daily volume before it shows data.
Content comes last, not first
Wording, links and attachments matter less than most advice suggests once authentication is in place. Some patterns still help: a link whose visible text shows a different address from where it points, a link shortener, a single large image with no text, or an attachment type mail services block, such as an executable. Change the content after the records are checked, not before.
What to ask your email provider
- Which services send mail as our domain, and is each one included in our single SPF record?
- Is DKIM switched on for each of those services, signing for our domain rather than theirs?
- Do we have a DMARC record, where do its reports go, and does anyone read them?
- Does our website send its form emails through our mail provider, or from the web server itself?
If customers say your contact form goes quiet, that is a different problem from email landing in junk: read how to trace a missing enquiry. For how email fits a small business’s wider set-up, see email for Irish businesses.