Why your emails go to spam, and how to fix it
By the Olvane team · Updated
Your email reaches the recipient, but it lands in their spam folder. No bounce, no error, just silence. It's one of the most frustrating problems in email because nobody tells you why.
Spam filters weigh dozens of signals, but in practice a handful of causes explain most legitimate mail ending up in spam. Here they are, roughly in the order you should check them.
1. SPF, DKIM or DMARC is missing or broken
This is the first thing to rule out, because it's the easiest to fix and the most damaging when wrong. Without these records, receivers can't confirm your mail is from you, and since 2024 Gmail and Yahoo treat unauthenticated mail far more harshly.
How to check: open a message you sent to a Gmail address, choose "Show original", and look for SPF: PASS, DKIM: PASS and DMARC: PASS at the top. Or run your domain through the email DNS checker.
Fix: follow how to set up SPF, DKIM and DMARC. Pay attention to duplicate SPF records and the 10-lookup limit, the two most common hidden errors.
2. Your domain is new
Mailbox providers judge a domain by its history. A domain registered a few weeks ago has none, and spammers register fresh domains constantly, so new domains are treated cautiously even when everything is set up perfectly.
Fix: there's no switch for this; reputation is earned. Start with a modest volume of mail to people who expect it and reply to it, and increase gradually over several weeks. Avoid sending newsletters or cold outreach from a brand-new domain.
3. The domain extension has a poor reputation
Some top-level domains are heavily used by spammers because they're cheap. Mail from those extensions starts with a lower score in many filters, regardless of who sends it. Spam-filter tests often flag them by name.
Fix: if you're choosing a domain for business email, a .com or your country's own extension is the safest choice. If you already have a lower-reputation extension, authentication and steady, wanted mail matter even more.
4. The sending server has no matching reverse DNS
Every server that sends mail should have a reverse DNS (PTR) record that points its IP address back to a hostname, and that hostname should point back to the same IP. Receivers check this, and a missing or generic PTR record, such as one your hosting company created automatically, is a strong spam signal.
A subtle version of this catches people running their own servers: a machine with both IPv4 and IPv6 may send to Gmail over IPv6, where the PTR record and SPF are often missing even though IPv4 is set up perfectly. Gmail is particularly strict about IPv6 senders.
Fix: if you use an email provider, this is their job. If you run your own server, set the PTR record at your hosting provider for every address that sends mail, or make the server send over IPv4 only.
5. Your IP address or domain is on a blocklist
Blocklists such as Spamhaus record addresses and domains that have sent spam. Shared hosting and cheap servers sometimes inherit an IP address someone else abused.
Fix: look your sending IP and domain up on the major blocklists. Each one explains how to request removal, which usually only works once the cause is fixed.
6. Recipients don't engage, or mark you as spam
Gmail and Outlook watch what recipients do. Mail that's opened, replied to and moved out of spam builds your reputation. Mail that's deleted unread or reported as spam damages it. Gmail asks bulk senders to keep their spam complaint rate below 0.3%, and ideally below 0.1%.
Fix: only email people who asked to hear from you, make unsubscribing easy (one-click unsubscribe is required for bulk senders), and remove addresses that never open anything.
7. You're sending too much, too fast
A sudden jump in volume looks like a compromised account. Gmail responds by deferring mail with temporary errors such as 421-4.7.28 and then filtering what it accepts.
Fix: ramp up gradually, spread large sends over time, and keep transactional mail (password resets, receipts) separate from marketing, ideally on its own subdomain.
8. The content looks like spam
Content matters less than it used to, but it still counts. Common triggers include:
- A single large image with little or no text
- Link shorteners, or links to domains with a bad reputation
- Mismatched links, where the visible text shows one address and the link goes to another
- No plain-text version alongside the HTML
- Attachments such as zip files or macro-enabled documents
9. The From address doesn't match how you send
Sending as you@yourcompany.com through a service that isn't authorised for that domain fails DMARC alignment, even if the service itself is reputable. The same happens when you send through a website plugin that uses the web server's own address.
Fix: authenticate every sending service on your domain (SPF or DKIM, aligned with the From address), or send from a subdomain you've set up for that service.
How to monitor your reputation
Two free tools show you what Gmail and Microsoft think of your mail:
- Google Postmaster Tools shows your domain's reputation with Gmail, spam complaint rate and authentication results once you send enough volume.
- Microsoft SNDS shows how Outlook.com sees your sending IP addresses.
Start with the part you control completely: run the email DNS checker and fix every problem it finds. Then give your domain time and send mail people want.