Boost your renewal rates with a foolproof membership renewal letter! Trying to write a membership renewal letter but don't know where to start?Here are 10 things your welcome letter or email to new members must include plus a template that can be customized for your organization. A formal letter for a membership typically follows a professional format and includes specific information related to the membership application or request. 1. Enter the date at the top of the letter. New member welcome letters are the perfect way to introduce your organization, reiterate its values and mission, drum up excitement, and express your gratitude. A "thank you for joining" membership letter should include a personalized greeting to the new member. Use the member's first name in your salutation. We hope the following sample Written Invitation to CSI Membership will provide a template for your chapter's individualized letter to prospective members.