The rate of complaints, bounces, and unsubscribes represents not only how satisfied your subscribers are with receiving your emails, but also how they feel about your entire email marketing strategy.
A person unsubscribes from a list when they no longer find the emails relevant, and they're likely to flag the emails as spam if they continue to receive them after unsubscribing. If a list is regularly sent engaging and timely content, the unsubscribe rate should be close to zero.
Bounces
A “hard” bounce
A hard bounce happens when an email address no longer exists or might have never existed. These situations can have dramatic consequences for the receipt of your emails. You can help avoid hard bounces by sending a subscription confirmation email.
An email address will be automatically removed from your list if a hard bounce occurs.
A “soft” bounce
A soft bounce occurs when the email address is currently unavailable due to a temporary problem.
An email address will automatically be removed from your list if four soft bounces occur. These emails are therefore removed in order to avoid spam complaints.
Bounce Rates
The bounce rate is calculated as follows:
Total bounces / Total number of people you sent your email to
The hard bounce rate should be no more than 1%.
Your bounce rate could be influenced by these factors:
Industry Type
Is your list up-to-date?
What is the frequency of your mailings? Each campaign's rate falls as you send more frequently.
Unsubscribes
The unsubscribe rate is calculated as a percentage of:
Total number of unsubscribes / Total number of people email was sent to
Always remember that unsubscribing is better than flagging you as spam. To add an unsubscribe link to your email, check out these instructions.
Complaints
The spam complaints rate is calculated as follows:
Total number of complaints / Total number of emails sent to specific internet service providers
As soon as someone marks you as spam, they are definitively removed from the list.
Use best practices to avoid complaints and send a test to yourself before sending out your campaign. You should never have more than 1 complaint for every 400 emails sent (0.25%).
Keep in mind that ISPs look at these numbers too. If your bounce or spam levels reach a critical level, it is only a matter of time before your emails get sent to a recipient's junk folder or get blocked permanently.
If you build a clean list and learn to avoid complaints you should be just fine.