What to write in cover letter when address is unknown?

Question

I want to apply for a job in a start-up that is not founded yet. I know the founders and they asked me for a formal application. How should I fill in the address field in the cover letter? As there is no name or address of the start-up yet, I cannot use

Company name
Jane Doe
John Done
Street
City

Dear Ms. Doe, dear Mr. Done,
...

Is it enough to just write

Jane Doe
John Done

Dear Ms. Doe, dear Mr. Done,
...

?

or should it be

Jane Doe
[email protected]
John Done
[email protected]

Dear Ms. Doe, dear Mr. Done,
...

?

Answer 1

Just use what you do know.

Write to the person you have the name of, there's no need to include their email addresses.

There's nothing else you need to do here.