Important information that should be in an internship offer letter. The internship offer letter should include the start and end dates of the internship, as well as the number of working hours per week.Found the perfect candidate to hire? We've got 7 types of job offer letter templates to choose from that'll help you seal the deal. Use an Internship Offer Letter form to offer an internship to a successful candidate. Dear (student's name):. I am pleased to confirm your acceptance of an internship as (Title) in the. DO be as precise and straightforward as possible in the offer letter. Subject: Congratulations on your Marketing Internship Offer! It is a formal way of inviting the candidate to explore and develop their career in the organization.