Why Emails Go to Spam and How to Land in the Inbox

Why do emails go to spam?

Emails go to spam because the mail provider weighs every message against signals of trust, and a message that falls short lands in junk or gets rejected.

The signals come in five families: identity, history, behavior (volume, pace, bounces), content, and how recipients react. None of them decides alone. An older, fully authenticated domain can afford a link. A week-old domain can afford almost nothing.

What are SPF, DKIM and DMARC, in plain English?

SPF, DKIM and DMARC are three DNS records that prove to the receiving server that a message came from your domain and not from an impostor.

SPF is the guest list of servers allowed to send for your domain. Connect a sending tool without adding it, and its mail looks forged.

DKIM is a digital signature on each message, checked against a key published in DNS, so the receiver knows the message is yours and unaltered.

DMARC sets what happens when checks fail: report only (p=none), send to spam (p=quarantine) or reject (p=reject). It also requires alignment: the "From" domain must be the one SPF or DKIM approved.

MX says where incoming mail goes, and a domain that can't receive replies looks suspicious.

To check, send an email to Gmail and open Show original in the message menu. Fix every FAIL before you touch the copy.

Why does a new domain go to spam?

A new domain goes to spam because it has no sender reputation yet, so providers have no history to judge it by.

A domain registered ten days ago, with no website, suddenly emailing hundreds of strangers is exactly what filters were built to catch.

Reputation takes time and clean behavior, and warmup is how it starts: a new inbox sends and receives small, gradually rising amounts before any campaign. In our experience, Outlook is more sensitive to domain age than Gmail. Our domain warmup guide has the setup. Reputation also covers the whole domain, so cold email from your main domain risks your invoices and proposals.

Do volume spikes cause emails to go to spam?

Yes. A sharp change in volume tells filters something changed at the sender, and they get suspicious.

An inbox that jumps from a few dozen emails a day to ten times that looks hacked, or like someone bought a list. In Israel, the classic spike is the campaign paused for the fall holidays that returns after Sukkot at full volume.

Grow by adding inboxes and domains, and raise each inbox's pace slowly. Identical text to hundreds of recipients is a pattern too, so we vary the message body.

How do bounces affect spam placement?

A bounce is an email returned because the address doesn't exist or can't receive mail, and many bounces tell the provider you're mailing an old or bought list.

Each dead address lowers the domain's score. At LeadBound every address is verified before sending and bounce stays under 2%. A campaign that crosses that line stops until the list is checked.

How many spam complaints are too many?

Keep complaints below 0.3% of your messages, and ideally below 0.1%.

That's the line in Google's sender guidelines, measured as the spam rate in Postmaster Tools: three complaints per thousand. Yahoo's sender best practices set the same 0.3% bar.

Someone with no easy way to opt out presses "Report spam." A closing line saying a reply of "remove" is enough prevents much of that, and it matters under Israel's spam law too.

What content sends emails to spam?

Content sends email to spam mainly when it looks like an ad.

• Links. Each is another domain to check, and shorteners are especially suspect. Our first email has none.
• Tracking pixel. Open tracking uses a tiny invisible image, a bulk-mail sign. Ours is off.
• HTML. Cold email is plain text, though Hebrew may need a minimal wrapper to display right to left.
• Promotional words. "Free," "exclusive discount," "click here."

Content usually decides only when everything else is borderline. The exception is Outlook, which is harder on text, so we give Outlook recipients a separate campaign with shorter copy. See our cold email templates.

What do Gmail, Yahoo and Outlook require from senders?

Since February 2024, Google and Yahoo require authentication and a low complaint rate from anyone sending to their personal accounts, and since May 2025, Microsoft requires full authentication from high-volume senders to Outlook.com.

Google's rules apply from February 1, 2024. Above 5,000 messages a day, a p=none DMARC policy is enough, the "From" field must align, and one-click unsubscribe applies to marketing mail. Google's FAQ says enforcement tightens from November 2025, including temporary and permanent rejections. Microsoft announced its rules on April 2, 2025, in a Microsoft Tech Community post, began enforcing on May 5, 2025, and said in an April 29 update that non-compliant messages will be rejected with the error 550 5.7.515.

One catch for B2B: Google says its guidelines don't apply to messages to Google Workspace accounts, and Microsoft's cover its consumer service. Most B2B recipients sit on business accounts. I'd meet the rules anyway, because in my view that's where providers start to trust a sender.

How do you find out why your email goes to spam?

Start from the symptom, since each one points to a different cause.

The last row is the hardest to accept, because no DNS record fixes an offer. Start with how to build an offer for outbound and the reply rate benchmarks.

How do you keep emails out of spam?

Build trust before the first message, in this order:

1. Send from a secondary domain, never your main one.
2. Set up SPF, DKIM, DMARC and MX, and confirm in Show original that all pass.
3. Warm up every new inbox. Ours get 14 days of warmup with a gradual ramp.
4. Verify every address before sending.
5. Split by the recipient's mail provider, Gmail and Outlook separately.
6. Write plain text, with no links or open tracking in the first email.
7. Raise volume slowly, and track bounces and complaints weekly.

That's how we set up every cold email campaign. Still in spam after all seven? Recheck step two: a new tool added without updating SPF breaks it.