Campaign Basics
Getting into the inbox
Why some campaigns land in spam, what damages a sending reputation, and the habits that protect it.
Last updated September 2, 2026
Sending an email is easy. Having it arrive is the hard part, and it depends less on what you write than on how the receiving mail systems judge your sending history.
What they are watching
| Signal | Effect |
|---|---|
| Bounces | Mail to dead addresses is the clearest sign of a poorly kept list. It hurts fast. |
| Spam complaints | The most damaging of all. A handful per thousand is enough to cause problems. |
| Engagement | Opens and clicks tell the receiving system people want your mail. |
| Consistency | A steady volume looks like a business. Nothing for six months and then fifty thousand looks like a list purchase. |
The habits that keep you in the inbox
- Verify addresses when you import. It is cheap, and it stops the bounce problem before it starts.
- Send to people who expect you. A list built from customers beats a list built from everyone in the database.
- Make unsubscribing easy. Someone who cannot find the link marks you as spam instead, which is far worse for you.
- Do not resend to people who never opened, over and over. Repeatedly mailing the unengaged is exactly the pattern filters look for.
- Warm up a new sending domain. Ramp the volume up rather than starting with everything.
NEVER SEND TO A BOUGHT LIST
It will bounce heavily, attract complaints, and can damage sending for every campaign you run afterwards — including the ones to customers who do want to hear from you. In many countries it is also illegal.
If a campaign landed in spam
Check the bounce and complaint numbers on your recent campaigns first — reputation is built over months, so the cause is usually two or three sends ago rather than the wording of this one.