When it comes to business correspondence, I always adhere to the principle that using personal emails and instant messengers is not always justified. Of course, it can be a convenient and fast way of communication, but in the long run it has its drawbacks. For example, personal email can be less secure and harder to track for corporate needs. This is especially important in cases where you need to maintain official document flow or save the history of correspondence for reporting. As for instant messengers, their use for business purposes should also be limited, as they do not always provide a sufficient degree of security and formality. They are more suitable for prompt, brief communications, but for serious business conversations it is preferable to use corporate communication channels, such as corporate email or collaboration systems, where all emails can be tracked and controlled. If you want to understand this issue in more detail, I recommend reading the article on https://mailtrap.io/blog/emails_vs_instant_messages/ Which explains well why it is important to distinguish between email and instant messengers for work tasks: