User-centric design: How to allow users to return a visit

How does "social design" allow users to return a visit (reengagement)?

Problem ( Problem )  
Some users on the website did not return a visit for some time.

Example ( Example )

Plaxo sends email to site users every once in a while, and the content is a member that the user may know and want to contact, so that users can visit the site again.

when to use ( Use when )  
1. What is the time to make a return visit to the users who have not visited for a long time;
2. When you need to tell users about some new features of the website;

Solution ( Solution )  
1. Allows users to voluntarily choose whether or not to accept e-mail messages sent on a regular basis at the time of registration;
2. Develop a schedule for e-mail messages that need to be sent;
3. It is best to focus on key features or new features in email;
4. If some users have not visited the site, you must be in the user agreed to accept the premise of the message, to send mail to attract them to visit; If the site's characteristics are based on relationships, sharing public data blocks from users ' friends, you should let users know what they are missing.
5. Before sending a request for a return visit to the user, should set a user how long did not come to send him the rules of the mail;
6. The message should contain a bold call action (called to action);
7. Each email content should be concise;
8. Send mail not too many times, the frequency can not be too high, otherwise it will make all the efforts of users to return a visit in vain.

Logical Basis ( rationale )
Making a return visit is a work that needs to be sustained for a long time, and in most cases the user can return a visit by sending a regular message (such as newsletter). Mail content is often diverse and can highlight themes, or some of the user's friends on the site.