Our email campaigns dropped from 3-5% reply rate to 1% overnight. I found the problem and fixed it - you'll never guess what caused it:

First, when I saw this, I thought our infrastructure was burned. That would've sucked, but there's not much we could do there other than implement back-ups.

Then I looked into it more, and realized that wouldn't make sense. We were following best practices and the infra was new. Something was up.

I was shocked by what I found when I dug deeper:

Our email signatures had phone numbers.

For the longest time, that was a normal thing to us...it helped us look more legitimate.

But after digging around, I realized our phone numbers were getting hyperlinked in the email.

We removed these and it was like magic - reply rate came back up.

The lesson:

If you're getting away with it, good for you.

But if your reply rate is low and you can't figure out why, try removing phone numbers from your signature.

It worked for us. Just saying.

Anyone experienced this?