Will I overwrite all my clients' data by importing a contacts file?

It depends, in the sense that there can be an overwriting of existing clients' information fields if you have these contacts in your import file. When importing contacts files, the system looks at the contacts’ email address and updates the name of the contact, if different. So, the email address is the filter and basis of comparison for avoiding double contact entries.

For example, if you have John Smith in your Console contacts list with the email address [e-mail] and you import a file where you have John Adam Smith with the same email address ([e-mail]), then the system updates the name to John Adam Smith. The same goes for the other columns in the import file and corresponding fields in the Console’s client information section (CONTACTS TAB > CLIENT NAME > PROFILE TAB > Client Information).