Contacts and channels
Which channel for which message
Email, SMS or WhatsApp: which arrives, which annoys, and which costs.
The same message performs differently depending on the route. It is not a matter of taste: each channel has a place where it is read and a threshold for what counts as intrusive.
| Channel | Read | Cost | Good for |
|---|---|---|---|
| When the inbox is opened | Same as the others | Anything with documents that needs reading properly | |
| SMS | Almost immediately | Same | Urgent things, and reaching people who do not use email |
| Immediately | Same | Third parties you already talk to there |
The practical rule
- Start with email: it costs the same as any other channel and carries detail.
- Escalate to SMS when email did not arrive or there is genuine urgency.
- Use WhatsApp only if you already have that relationship; otherwise it reads as intrusion.
Watch out
Sending the same notice on all three channels at once does not triple delivery: it reads as harassment, and the first time you do it you will earn a block.
When to switch channel
If the notice was opened and there is still no reply, switching channel adds nothing: the message arrived. Switching helps when the previous one did not arrive — a bounced email, or three unopened notices.
Worth knowing
For people working on site or on the road, email arrives late and a phone always arrives. There, SMS is not chasing: it is the right channel from the start.
›Can I choose the channel per contact?
Yes, and it is worth it for the ones you know do not read email.
›What if I do not have their mobile?
Only email remains. Asking for the mobile when creating the contact saves weeks later.
›Does WhatsApp have to be a business number?
Yes, a verified one. A personal number inspires no confidence and cannot be audited.
A real case
The situation
A construction firm cannot get paperwork from site managers who never open email.
What you do
- Sets SMS as the preferred channel for that group
What you get
Delivery goes from days to hours, because the notice lands where that person actually looks.
The situation
An urgent notice goes by email and is read the next day.
What you do
- Uses a more immediate channel for what is urgent
What you get
The urgency arrives in time.
The situation
A long link is sent by message and gets truncated.
What you do
- Sends the link on a channel that preserves it
What you get
The link arrives whole.
The situation
Sensitive documentation goes out on any channel.
What you do
- Uses the channel that matches the content
What you get
Sensitive material travels where it should.
The situation
Channels are combined and the recipient gets three notices.
What you do
- Defines one channel per notice type
What you get
Nobody receives the same thing three times.
The situation
The channel is chosen without knowing what the recipient uses.
What you do
- Asks or records their preference
What you get
The first send already works.
This article answers
- best channel to request documents
- when to use whatsapp instead of email
- send notices by sms
- the client does not read emails