It’s Kate from Selzy here. Today I want to talk about a specific kind of email marketing pain.

Not the campaign that went flat because the offer was wrong or the subject line was not catchy enough. I mean the one that shouldn't have gone flat in the first place. The one where the copy was good, the design was even better, the timing was right — but then the numbers came back, like a low open and click rates, and they were disappointing. What did you miss?

Sometimes the answer isn't about creativity. It's in a layer most of us skip — the five minutes between "it’s done done" and "send".

The invisible filter between your email and the inbox

Spam filters don't care that your subject line was catchy, they're scanning for signals — specific words, red flags, structural patterns. Here are the five most common ones:

• Spam words — certain words alert spam filters regardless of context. "Save $", "act now", "100% free" aren't banned, but they add up. Check before you send.

• Email size over 102KB — Gmail clips anything above this, cutting off the bottom of your message. That CTA you put at the end? Part of your audience never saw it. Link to files instead of attaching them, and trim the rest.

• Shortened links — Bitly and its counterparts are a spam classic. Use full URLs, embedded in anchor text if they're too long.

• Too little text — filters distrust image-heavy emails with minimal copy. So do subscribers with disabled images. Aim for at least a paragraph or two of real text.

• Missing alt text — if an image doesn't load, alt text is all your subscribers have. Write it for every image.