Sharing notes on one email

we are 3 people using one email account. However, so far we haven’t found any useful way, how to let each other know progress of certain conversations other than separating emails into many folders which then makes it harder to find them. Labels are not visible to others and the same goes with notes. Is there any way how to make it visible for others that someone is dealing with the email hopefully in a better way than folders?

This option is only available with Exchange accounts.

If all three are sharing the same Exchange account, if one of you add a quick note to an email, the others will see it as well.