How should I write an email to one of my professors when I am sick, and therefore unable to attend a class?

I was an ESL instructor at a university in South Korea and some students had been taught a lot of idioms and hadn’t been taught, or didn’t have a feel for, different levels of formality in English. My answer is largely directed at them. People with good English but also for some reason concerned about this question might find some value in it.

“Professor .”

By courtesy I was called ‘professor’ even while not doing formal research or other duties normally expected of other professors. But in my case, It would be “Professor Dean’. Students called me ‘Brian’ in class, but in this sort of email, the family name is better.

“I am unwell and do not expect to be in class . “ Either: “I was not able to complete my assignment and I will bring it to your office when I am able.” or “My classmate is bringing my assignment to class.” or, “Due to my illness, I will not be able to email my assignment to you until ”.

Sincerely,