If your complaint rate is rising it's best to examine the root of the problem, which is asking the question why these subscribers complaining? Maintaining a high complaint rate can lead to dramatic consequences, including having your account be terminated. 

1. Have the user double-opt in.

Make sure the user is interested in your product or service by having them double opt-in or confirm them as a member of your site. Adopia has a unique double opt-in feature that will only allow visitors who double opt-in to become part of your list. This will insure that quality leads are entering your user list instead of bogus ones. 

2. Examine your traffic sources

It's important to know that people are coming to your website that are interested in your product or service. Sometimes users unintentionally opt-in to a website, because they were trying to accomplish another goal or didn't understand the websites purpose. When sending to these users, they often will not even remember opting-in to your website causing them to click the spam button when they receive your email. 

3. Be clear on what the users will receive. 

Be direct with your subscribers on what they can expect to receive. Any unfamiliar or unexpected messages may cause subscribers to mark the mail as spam. Let subscribers know about the content you send and what time you will send it. 

4. Make it easy for users to unsubscribe to your mailing list

It's a fact that users will want to unsubscribe to your mailing list. Providing users an easy way to unsubscribe from your list will prevent them from them potentially becoming frustrated and marking your future messages as spam. 

5. Don't overload users with messages

Over aggressive mailing can turn users off and they may potentially mark your messages as spam. It's best to try out different frequencies when mailing until youcan accurately gauge what your user list is comfortable with. 

6. Present a consistent image

Make sure your subscribers are familiar with your brand and your image. If you make too many changes and your brand becomes inconsistent you risk your messages being recognized as spam.