Why cold emails land in spam, and how to get back to the inbox

An email that lands in spam doesn't bounce and doesn't warn you. It just goes quiet. Replies dry up, and most teams blame the subject line.

The words are rarely the problem. When cold email lands in spam, the cause usually sits further upstream: the domain, the mailbox, the volume or the list. Work through the causes in order, and the first four explain most cases.

Why are my emails going to spam?

Mailbox providers decide where an email lands from the sender's track record and the signals each email earns: bounces, spam complaints, replies, and emails moved out of spam. These are the usual causes, most likely first.

1. Missing or broken authentication. No SPF, DKIM or DMARC, two SPF records, or a sending service without its own DKIM key. Without all three records, email is suspect from the first message.
2. New or unwarmed mailboxes. A mailbox with no history that sends cold email in its first week looks exactly like a spammer. It needs 2 to 4 weeks of warmup first.
3. Too much volume per mailbox. A warmed mailbox pushed from 40 to 150 cold emails a day spends its reputation in days. Hold each one at 30–50 a day.
4. A high bounce rate. A list full of old or guessed addresses tells providers you don't know who you're emailing. Treat anything above 2% of sends as a problem.
5. Spam complaints from poor targeting. Email people with no reason to care, and some of them press the spam button. A handful of complaints weighs more than hundreds of ignored emails.
6. Sending from your main domain. Cold email on the domain that carries invoices and newsletters shares one reputation with all of it, so cold email belongs on separate sending domains.
7. Links, tracking and attachments. Several links, link shorteners, tracking pixels and attached files make a cold email look like bulk mail.
8. Content. Last, and least likely. A plain email to the right person rarely trips a filter on its words alone. Misleading subject lines, all caps and heavy formatting still do.

Check and fix, cause by cause

Fixing the copy while a DKIM key is missing changes nothing.

How to tell if your emails are going to spam

Three checks find most problems:

• Check the records. Look up SPF, DKIM and DMARC on every sending domain. One SPF record, a DKIM key for every service that sends, and a DMARC policy published.
• Send test emails. Send from each mailbox to a few test addresses at different mailbox providers, and note where each one lands. One mailbox in spam points to that mailbox. Every mailbox in spam points to the domain.
• Read the bounces and complaints. Count them per mailbox, per week. Bounce messages often say why: an address that doesn't exist, or a block on the sender.

In this example, Ostervane sends from 10 mailboxes on getostervane.com. Test sends put 3 of them in spam. All three started cold email in their second week, at 60 a day. The records pass and bounces sit at 1%. The cause is volume on unwarmed mailboxes, not the email.

How to get back to the inbox

1. Slow down. Cut cold volume on the affected mailboxes to 10–20 a day.
2. Rest the worst mailboxes. Stop cold email entirely on any mailbox landing in spam, for 1–2 weeks.
3. Fix the cause. Correct the records, verify the list and remove every address that bounced, or tighten who you're emailing.
4. Keep warmup running. Warmup keeps earning positive signals while cold volume is down, and that history is what brings a mailbox back.
5. Test, then ramp up. When test sends land in the inbox again, restart at 10 a day and step back up to 30–50 over a few weeks.

If a sending domain still lands in spam after a few weeks of rest, retire it and move its volume to a fresh, warmed domain. That's what separate sending domains are for.

How Leadgenerator.io keeps mailboxes out of spam

When you add a sending domain, Leadgenerator.io shows you the exact DNS records to add, creates 5 mailboxes as soon as the domain verifies, and starts warmup automatically. Warmup keeps running in the background after cold sending begins, and volume caps hold each mailbox at 30–50 cold emails a day.

Agents find the right people at companies that fit your description and write a personal email for each one. Suppression lists keep customers, open opportunities, partners and competitors out of outreach, cooling periods of 60–90 days stop anyone being contacted twice in a quarter, and one switch stops all outreach while you fix a problem.