Earlier quoted context omitted.
Emojis and emoticons in any serious piece of communication are simply unprofessional and insincere. Do not use them, unless your intent is actually to piss your recipient off. Textbook example is the recent fiasco over at Linus Tech Tips, where they even used an emoji in an email to Billet Labs saying they "accidentally" auctioned off Billet's stuff. Anyone worth their paycheck doesn't use emojis in business communiq…
What's your opinion of slack? Seems to be the gold standard of team communication platforms (all other platforms follow their lead) and emojis are an integral part of it.
If it's actual business communications, no emojis.
What matters isn't the medium, it's the context concerning the communication.