Why your outreach emails land in spam (and how to fix it)

Your emails go out, don't bounce, and yet nobody replies. Then a prospect you know tells you they found your message in their junk folder. It's one of the most frustrating problems in email outreach, because it's invisible: no tool warns you that an email has landed in spam at the recipient's end.

The good news is that the causes are almost always the same, and you can check them in a logical order.

How to tell whether you're in spam

Since the recipient won't tell you, you need to measure it another way:

• the warmup inbox placement rate: if your mailboxes are part of a warmup network, you know exactly what proportion of their messages land in other participants' inboxes. It's the most reliable indicator;
• a test on your own addresses: send your campaign email to a personal Gmail address and a personal Outlook address, and see where it lands;
• a content test with a service such as mail-tester, which gives you a score and lists the technical issues;
• a sudden drop in reply rate on a campaign that was working.

A sudden drop is rarely caused by the message itself. It almost always points to a reputation or configuration problem.

Cause 1: authentication

This is the first thing to check, because it's the easiest to fix. A missing or duplicate SPF record, a badly published DKIM key or a missing DMARC record is enough for Gmail, Yahoo and Outlook to filter your messages, and they now require all three. Also check alignment: the domain that signs the message must be the one in the From address.

Everything is explained in our guide to SPF, DKIM and DMARC. In SmartOutbound, these records are checked every day for all your domains.

Cause 2: a domain or mailbox that is too new

A domain bought ten days ago, a mailbox sending 50 emails in its first week: that is exactly the profile filters associate with spammers. The fix is well known, but it requires patience: a two- to four-week warmup and a gradual ramp-up.

Cause 3: volume and pacing

Even an old, well-configured mailbox will eventually be filtered if it sends too much, too fast. The warning signs are:

• a daily volume that suddenly doubles;
• burst sending, every few seconds;
• sends at night or at weekends, out of line with the sender's normal activity;
• a mailbox that never receives replies but sends a lot.

Stay at around 25 to 30 outreach emails per day per mailbox, leave several minutes between sends with some variation, and spread the volume across several mailboxes rather than pushing one mailbox hard.

Cause 4: invalid addresses

Every email sent to an address that doesn't exist bounces. Once bounces rise above a few per cent, providers decide you don't know your recipients, which is the hallmark of unsolicited bulk sending.

Check your lists before sending (syntax, whether the domain exists, the receiving server), remove disposable addresses, and don't reuse an old file without checking it. Invalid addresses should be removed permanently after the first bounce. SmartOutbound runs these checks on import and just before the first email to each contact, and automatically pauses a campaign if its bounce rate goes above 5%.

Cause 5: complaints

When a recipient clicks 'Report spam', it's the most serious signal there is. Gmail asks senders to stay below 0.3% complaints and recommends aiming for less than 0.1%. In outreach, where recipients never asked to hear from you, those thresholds are quickly reached if your targeting is poor.

To limit complaints:

• write only to people for whom your message is relevant;
• include a clear unsubscribe link in every email, and honour the unsubscribe immediately. A prospect who can't see how to unsubscribe will click 'spam';
• add the one-click unsubscribe header, which displays an 'Unsubscribe' button in Gmail and other email clients;
• stop the sequence at the first sign of annoyance.

Cause 6: content

Content matters less than people think, but it does matter. The elements that carry the most weight are:

• multiple links, especially shortened links or links to different domains;
• images, and even more so an email that is entirely an image;
• attachments;
• heavy HTML formatting, which looks like a newsletter;
• words in capitals, repeated exclamation marks, exaggerated claims with numbers.

An outreach email should look like an email a person typed by hand: simple, short text, with no link in the first message. For structure, see our guide to the first email.

Cause 7: domain extension and domain reputation

Some domain extensions (.shop, .online, .store, .fun, .space, .cfd in particular) are used so heavily by spammers that filters treat them with suspicion by default. If your mailboxes on those domains have a noticeably worse inbox placement rate than the others, it's not your imagination. Our article on dedicated domains explains how to choose.

The plan to fix it, in order

If you think you're in spam, proceed as follows:

1. pause the campaigns for the mailboxes concerned, but keep warmup running;
2. check authentication SPF, DKIM and DMARC for each domain;
3. check the bounce rate on recent sends and clean your lists;
4. compare the mailboxes with one another: if only one is affected, it's that mailbox or its domain; if all are, it's the content or the list;
5. simplify the message: remove links, images and formatting;
6. resume gently, at 5 or 10 emails per day, and increase only when the inbox placement rate is back above 90%.

Allow one to three weeks to rebuild a decent reputation. Pushing harder during that time only makes things worse.

Prevention is better than cure

Most of these causes can be avoided with simple settings, applied from the start and maintained over time: verified authentication, ongoing warmup, capped volume, checked lists, immediate unsubscribe. SmartOutbound applies this foundation by default to all your mailboxes. Start for free and check your mailbox health from the first week.