LINE: Pros: everyone's got it. Cons: no contact organization/sorting options. Must contact each client individually to protect each users contact info (group chat displays everyone's info).

EMAIL: Pros: put everyone in bcc to protect customer privacy. Cons: I feel like the majority of my customers don't check it.

I think I've actually lost a few potential customers because of unread emails. I'd run a trial and tell them that I'll contact them via email - no response. I understand that a percentage potentially are not interested but I'm sure that many just don't check it.

PHONE: Pros: Guaranteed to clearly communicate message. Cons: need to contact each person individually.

I also end up doing unintentional cold calling with potential clients. Sometimes I need a response and when I call, I feel like I'm pressing the customer for an answer.

With a growing client base, I've been looking for a way to send out group notifications. One example would be to notify of schedule changes, cancelled lessons, holidays. I HATE having to message 30 people individually. I also am afraid of missing a few contacts in the process.

Tldr; how do you notify the clientele of generic information? What is the norm in this country?