First, the word 'dear' should be capitalized. Second, don't just leave it as 'Dear Mr." Make it, 'Dear Mr So-and-so.' If you don't know the name of the person to whom you are writing, 'To Whom It May Concern' is perfectly acceptable. I'll leave the punctuation up to you. Nowadays, many people don't even put a period after 'Mr' (myself included). Likewise, many people do not end the salutation with any punctuation at all. This is a judgment call that you'll have to make -- and be responsible for. Just take into consideration how formal your correspondence is supposed to be and act accordingly.
I would address it to Mr and Mrs David Keys. For the salutation I would use Dear Mr and Mrs Keys.
"Hi" or "Mr./Miss. Name" can be used instead of dear.
Dear Mr. Capote was created in 1983.
Dear Mr. Prohack was created in 1949.
Mr. President
Dear Mr. Henshaw was published in 1983.
Dear Mr. Wonderful was created in 1982.
If you know their name, then use sincerely. If you don't then use faithfully. Thus Dear Mr Bloggs - Yours Sincerely Dear Sir - Yours Faithfully
Dear Mr. Fantasy was created in 1967-12.
The duration of Dear Mr. Wonderful is 1.67 hours.
i want to send a disruptive email to the CEO of a company. Should I start by "Dear Mr. Gomez" or " Dear Mr. Daniel Gomez"
dear Sirs: