Use a comma after the name.
EXAMPLE: Dear Mr Smith,
Dear Dr Smith,
Do not use a full stop after the abbreviated title.
AVOID: Dear Mr. Smith,
This applies to "team," "colleague," "employees" or anything else…
EXAMPLES: Dear Team,
If you are unsure of a woman's title preference, use 'Ms' (pronounced 'Miz'). This is a neutral and professionally acceptable title that does not indicate whether a woman is married or not. It is the equivalent to the male title 'Mr'.
EXAMPLE: Dear Ms Swift,
AVOID: Dear Mrs Swift,
AVOID: Dear Miss Swift,
If the woman refers to herself in previous correspondence using one of the above titles (i.e. Mrs or Miss), then use that.
EXAMPLE: Dear Mrs Swift,
If you do not know the recipient’s gender, you may use the person's full name and omit the title.
EXAMPLE: Dear Taylor Jones,
There is almost no excuse for not being able to find out the name of the person you are writing to, so always try.
If you still cannot find the name, then use the anonymous phrases such as 'Dear Sir/Madam' or 'To Whom It May Concern' as the last resort - but first consider alternatives:
EXAMPLE: Dear [Job Title],
EXAMPLE: Dear Hiring Manager,
EXAMPLE: Dear HR Manager,
If you do not know the name of the person you are writing to, cannot find it out and there are no suitable alternatives, then use this salutation.
EXAMPLE: Dear Sir/Madam,
If you do not know the name of the person you are writing to and wish to address the organisation more generally, then use this phrase.
If you must use the phrase 'to whom it may concern', we recommend capitalising the phrase since you are replacing a person's name with this salutation.
EXAMPLE: To Whom It May Concern,
AVOID: To whom it may concern,
We recommend 'Dear Sir/Madam,' as best of the bad bunch of anonymous greetings (above).
Learning English 'FCE Formal Letter' Retrieved from http://www.rubenvalero.com/english/content/fce-formal-letter-or-email
Oxford Living Dictionaries 'Choose the right greeting and sign off'. Retrieved from https://en.oxforddictionaries.com/writing-help/choose-the-right-greeting-and-sign-off
Oxford University Press 'Sample formal letter' ["PDF file] Retrieved from https://oup.useremarkable.com/production/images/uploads/3687/original/uk_sample_formal-letter.pdf