Working part-time in customer support, I have to deal with the same situation very often, and I often have to google for "awkward" names, too.
What I usually end up with when nothing helps, is either of the following:
I just drop the "Mr/Ms" altogether. "
Dear Maria Cannavaro", "Dear Wei Li", etc.
If the person is located in the US, I assume that they do not object to being addressed by their first name. "
Dear Maria",
"Dear Alex".
Also, I might sometimes use a simple "Hi there" or "Hi", but usually only if the person has previously contacted me using a similar informal address.
Lastly, sometimes people do ask me for a license key in a formal, polite way, but sign as "B. Smith".
In that case, they either don't really care how I address them, or they don't want me to figure out their gender or full name for some reason, which I must respect.
Not one of these people has ever objected to my use of "hi".
english.stackexchange.com/users/300/RegDwigнt
Given our construction of gender, 'tis usually a far greater sin to falsely assign a gender than to avoid formal address.
english.stackexchange.com/users/975/msw
For Wei Li , I would not break up the name and say Dear Wei or Dear Li , because some people use reverse order with surname first, and some people have compound names.
english.stackexchange.com/users/914/Picturepocket
If you are lucky there may be a title you can choose.
"Dear Professor Doe" is safe for either gender.
Likewise of "Doctor" (either the academic or the medical/veterinary/dental variety), and for military, police or clerical ranks.
Failing that I go with "Dear Full Name" as others have suggested, as it contains nothing that might offend and still conveys a basic degree of formality and respect.
english.stackexchange.com/users/2851/dmckee --- ex-moderator kitten
In 2015, ODO added Mx (pronounced like "mix") as a gender-neutral pronoun.
See definition 2 for Mx on ODO Pronunciation:
/məks/ /mɪks/
NOUN
A title used before a person’s surname or full name by those who wish to avoid specifying their gender or by those who prefer not to identify themselves as male or female "To me, Mx Bond embodies the very best kind of girl a boy could ever grow up to become." Origin 1970s: apparently from M (as in Mr, Mrs, Ms, etc.)
+ X1 (probably denoting an unknown or variable factor or quantity). For further reading: Mx (title) on Wikipedia
The word was first proposed in the late 1970s.
The "x" is intended to stand as a wildcard character, and does not imply a "mixed" gender.
Ngram shows some data , but it's unclear what Mx means there.
english.stackexchange.com/users/50044/NVZ
When faced with this problem in an email (my most normal scenario), I look at the signature and use that to address the person.
english.stackexchange.com/users/2386/Jonathan Leffler
When communicating with foreign cultures, the gender of the addressed person is not always clear from the name. What would be a professional way to address someone in this situation. ( Dear Mr or Ms SomeForeignName looks awkward). A hack I generally use is to do a google image search for the name, but this isn't always accurate in all cultures. What's the solution here?
How should I address someone with a known name and unknown gender?
english.stackexchange.com
<ambiguity><salutations>
english.stackexchange.com/questions/2353
english.stackexchange.com/users/45/Midhat
It is generally considered a greater sin to falsely assign a gender than to avoid formal address. If someone has previously contacted you in informal address, you could simply say "Hi there". If the person in question has a title, such as "Professor" or "Doctor", you could use this, but alternatively, you could simply address them by their full name or the name written in their e-mail signature. It is important not to make a mistake with gender so in the absense of any other option go for a gender neutral salutation like "Hi there"
It is generally considered a greater sin to falsely assign a gender than to avoid formal address. If someone has previously contacted you in informal address, you could simply say "Hi there". If the person in question has a title, such as "Professor" or "Doctor", you could use this, but alternatively, you could simply address them by their full name or the name written in their e-mail signature. Go with  "Dear Full Name". Given our construction of gender, 'tis usually a far greater sin to falsely assign a gender than to avoid formal address.  Dear Professor or doctor is safe for either gender if applicable.
The first name may be used or Mr/Ms may be avoided altogether. In informal communication, "Hi" may be used, for example. There may be a hint in the signature. When faced with such a situation, you may want to simply drop the formal address and use either a less formal address or their full name. Alternatively, you could use the name in their e-mail signature.
If unsure of the gender just begin with Hi or Hi there. Gender is a sensitive issue so best to avoid getting it wrong. Another option is to use the full name as in Dear Wei Lu. If there is a title, use that, e.g. Dear Doctor. There is the address form Mx but it's not in common usage. You could check the signature and use that.
Go with  "Dear Full Name". Given our construction of gender, 'tis usually a far greater sin to falsely assign a gender than to avoid formal address.   Dear Professor or doctor is safe for either gender if applicable.
When faced with such a situation, the safect option is probably to drop the formal address and simply use their first name. You might want to use a less formal greeting to avoid problems in this situation. You might consider addressing the recipient using the name in their e-mail signature.