An informal letter or email is usually between people who know each other fairly well. In addition to giving news, they are often used to request information, congratulate people, give advice and ask questions. There are a lot of similarities between informal letters and conversation. Informal letters ask a lot of questions, show interest and enthusiasm, and imagine a lot of shared information.
Salutation or Greeting
Body (Giving news, apologies, invitations, request, congratulations, making suggestions)
Closing
Informa Letter (Notes)
Informa Letter (Topics)