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."Dear Parents, I am writing to thank you for two things. I would like to welcome back our students from last year, and I'd also like to extend a warm welcome to any new students. 1. Enter the date at the top of the letter. Childcare available. Discover expert tips on writing the perfect welcome letter to new employees, complete with customizable templates for a personalized touch. Here are 10 things your welcome letter or email to new members must include plus a template that can be customized for your organization. 1. Enter the date at the top of the letter. It feels a little bit like showing up to a party where you don't know anyone else there.