Alexey

Was the email sent to two people?

When the sender wrote "both", did he/she mean both people he/she sent the email to?

If the sender sent the email to two people, then he should have said Hi (name 1) and (name 2) e.g., Hi Alexey and Richard

Using people's names, especially in business, is proper, polite and professional.

After 28 years as a business consultant, I have never seen an email "Hi both"

Alexey

Sometimes, in business, people know each other quite well because they have met before or spoken or emailed each other often.

If the email sender and the recipients (the people who the email was sent to) know each other well and work together often, then the email can be more informal, more friendly.

So, Hello both would be OK, but business relations should not be too informal - they should be a bit formal.

Honestly it makes me laugh... I hardly can imagine the quality of company culture where such greeting would be apropriate:)

Hi Richard.

Yes. The email was send to 2 people. Names of all people had been known before.

So it was 3 participants in email.