Measuring open and click-through rates can show you just how successful your e-mail marketing campaigns are.

But on the flip side, there’s another metric you should measure: the “complaint rate.” And if it’s too high, you could be in trouble.

Complaint rate is the percentage of recipients receiving your e-mail who complain to their ISP that you are spamming them.

According to e-mail deliverability expert Kevin Senne, the complaint rate should not exceed 0.2%, meaning a maximum of 2 spam complaints per 1,000 e-mails broadcast.

Warning: a number of e-mail services will refuse to distribute e-mails to your list if your spam complaint rate exceeds 0.2% or even 0.1%.

To lower your complaint rate to acceptable levels:

1. Make your e-mail copy more content-heavy…and less sales-oriented.

2. Ask subscribers what they want to read in your e-mails and give it to them.

3. E-mail your list less frequently.

Source: The Marketing Report