What is good WhatsApp broadcast etiquette for a small seller?
Four habits of good broadcast manners, permission, frequency, timing and an easy way out, that keep customers happy to hear from you.

A customer's phone is personal space. When you message them on WhatsApp you are walking into the same room where their family talks. Good manners there are not a marketing trick. They are the difference between being a welcome neighbour and a nuisance.
Platform rules and policies change, so I will not state what WhatsApp currently allows or requires. Check the official WhatsApp help pages for the current terms before you build a routine around any feature.
One, get permission first
Only message people who have said you can. That might be a customer who ordered from you and agreed to updates, or someone who asked to join your list. Do not add people from a phone book, a relative's contacts or a group chat without asking. How to get customer permission for WhatsApp updates gives you the wording.
Keep a simple record of who agreed and when. A column in a spreadsheet is enough.
Two, keep frequency light
Think of how often a friend would welcome a message from a shop. For most small sellers that is rarely, tied to real news, not to a schedule. A new product, a restock, a delivery cut-off. If you have nothing useful to say, say nothing. There is more on this in how often you should send a WhatsApp broadcast.
Three, mind the timing
Send when people are likely to be awake and free. Avoid very early mornings, late nights and meal hours. If you know your customers' routines, such as school pick-up times or office hours, work around them. Festivals and family occasions are busy times, so keep messages short then.
Time of day is a courtesy. I will not claim any specific hour works better, since it depends on who your customers are.
Four, make leaving easy
Every broadcast should tell people how to stop. A line such as "Reply STOP and I will remove you" works. When someone does reply, remove them promptly and thank them. Never argue or ask why. How to let customers opt out of WhatsApp broadcasts covers this in detail.
Five, stay personal
Write in your own voice. Use the customer's name where you can. Avoid forwarding messages that look like chain letters. If the message could have come from any shop, rewrite it so it could only come from yours.
Six, answer replies
A broadcast invites replies. Check your messages after you send and answer promptly. Ignoring replies after a broadcast feels rude, and it wastes the chance to talk to someone who is interested right now.
What to avoid
- Sending the same message twice in a day.
- Adding people to groups without asking.
- Using fear or false urgency.
- Sharing customer numbers with anyone else. Customer data is theirs, and keeping your customer data yours explains why handling it carefully matters.
- Sending long promotional blocks.
The test
Before you send, ask whether you would be happy to receive this message from a shop you bought from last month. If yes, send. If not, improve it or skip it. Good etiquette costs you nothing and protects the relationship you worked hard to earn.