Formal e-mail. B2

 https://learnenglishteens.britishcouncil.org/skills/writing/upper-intermediate-b2-writing/more-formal-email

https://www.wallstreetenglish.com/blog/how-to-write-formal-emails-in-english

https://www.inenglishwithlove.com/blog/how-to-write-an-email-in-english

https://oxfordhousebcn.com/en/how-to-write-a-b2-first-formal-email-letter/

https://teacherphill.com/fce-how-to-write-an-email-letter/