Those who have worked with me, went to school with me, or are friends or family have leeway in how they address me. They’ve earned it by going through things with me or just by putting up with me.
If you are a vendor making a cold or warm contact via e-mail, you can either use a formal address using my last name, or you may be bold and use my first name as on my business card, LinkedIn profile, or as spelled out in my e-mail address. Note that a difference between the two may indicate specific preferences about how I prefer to be addressed.
If you use a nickname that is never used in any of my contact information, you’re making some big assumptions about the familiarity of our relationship. They’re also called “incorrect assumptions”.