I think, it may depend on the purpose of this e-mail. Say, when I send my resumes, if I know the person's name, I always start with Dear Mr. John Adams
If I don't know person's name, I write Dear Sir/Madam,

I think, this would be appropriate for an e-mail. If it would be a mailed letter, it could be started from your phrase. However, I'm not an expert (obviously) and just stated this as I see it.

>I have to send e-mails.
>
>What would be a good way to start that message.
>
>"To whom it may concern," is one.
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>If the name of the recipient is John Doe "Mr. Doe," could be another
>
>What would you suggest as alternatives?