The Problem
You send a perfectly normal email to a customer and it never arrives. Or it ends up in their spam folder. They never see it. You look unprofessional, or worse — they think you never responded.
This happens more than you'd think, and it's gotten worse as spam filters have gotten smarter. The same AI that catches actual spam can sometimes flag your legitimate business emails too.
How Spam Filters Work
When you send an email, it doesn't just go straight to the recipient's inbox. It passes through filters that check a bunch of things:
- Who's sending it? — Is the sender's domain properly authenticated?
- Where is it coming from? — Is the sending server trusted?
- What does it say? — Does it contain spammy words, suspicious links, or misleading content?
- What's the sender's reputation? — Have emails from this address been marked as spam before?
Modern spam filters use AI to make these decisions, and they get better (and pickier) over time.
Common Reasons Your Emails Get Flagged
Your domain isn't set up properly
This is the #1 reason legitimate business emails hit spam. There are three DNS records that prove your emails are really from you:
- SPF — Tells email servers which systems are allowed to send email from your domain
- DKIM — Adds a digital signature that proves the email wasn't tampered with
- DMARC — Tells receiving servers what to do if SPF or DKIM fail
If these aren't set up, email providers like Gmail and Outlook are increasingly likely to reject or spam your messages. Google and Yahoo now require all three for bulk senders.
You're sending from a free email address
Sending business emails from @gmail.com or @yahoo.com can trigger spam filters, especially if you're sending to multiple people. A custom domain (@yourbusiness.com) with proper authentication is much more trustworthy.
Your content looks spammy
Even innocent emails can trip filters if they:
- Use ALL CAPS in subject lines
- Include too many links or images with very little text
- Have phrases like "Act now!" or "Limited time offer!"
- Include attachments that look suspicious
Too many people are marking you as spam
If recipients keep hitting the "report spam" button on your emails, your sender reputation drops. This can happen if you're emailing people who didn't ask to hear from you.
How to Fix It
1. Set up SPF, DKIM, and DMARC
These are DNS records that authenticate your email. If you're using Google Workspace or Microsoft 365, they give you the exact records to add. It takes about 15 minutes. If you're not sure how, we can do it for you.
2. Use your business email domain
[email protected] is always more deliverable than a free email address.
3. Keep your content clean
Write emails like a human. Avoid spammy formatting. Include a clear subject line and a reasonable text-to-image ratio.
4. Don't email people who didn't sign up
Only send marketing emails to people who actually opted in. This keeps your sender reputation healthy.
5. Check your reputation
Free tools like Google Postmaster Tools let you see how Gmail views your domain's reputation. If it's low, the steps above will help improve it.
The Bottom Line
Email deliverability is a real thing that affects real business. The good news is that the fixes are straightforward — proper domain authentication solves most problems. It's a one-time setup that pays off every time you hit send.
Having email problems? Get in touch and we'll figure out what's going on.