Why the format matters
WhatsApp needs every number in full international form — country code plus number, like 919876543210. A missing 91 or a leading 0 means the message fails, and duplicates mean the same customer gets it twice (and you pay twice).
Clean list, then a careful send
Message only customers who agreed to hear from you — how to collect opt-ins. Then send from Excel with the bulk WhatsApp guide, and keep your account safe with how to send in bulk without a ban.

