How I Send WhatsApp Campaigns to 500 Contacts From an Excel Sheet (Step-by-Step)
I had 500 phone numbers in a spreadsheet and a promotion that expired in 72 hours. The WhatsApp Business app has a broadcast list limit of 256 contacts — and those contacts have to have your number saved first, which roughly 60% of mine had not done. SMS bulk tools cost $0.08 per message, which at 500 contacts added up to $40 for one campaign. Email open rates from my list were running at 11%. The only channel that worked for my audience was WhatsApp. I needed to send 500 WhatsApp messages from an Excel sheet and I needed to do it fast. Here is exactly how I do it now.
What the OT1-Pro Campaigns feature actually is
Campaigns is a module inside OT1-Pro that lets you send bulk WhatsApp messages to lists of contacts imported from an Excel file. You do not need to know anything about the WhatsApp API. You do not need each contact to have your number saved. You prepare your list, write your message with personalisation placeholders like {{firstname}}, and the system sends on your behalf through the connected WhatsApp Business API number.
This is not a mass-spam tool. It is designed for contacts you have genuine business relationships with — customers who have bought from you, people who opted into updates, leads who reached out through your WhatsApp business number. Using it on cold lists violates WhatsApp's terms and will get your number flagged. Used properly, delivery rates run at 92–96%.
The step-by-step campaign workflow
Here is exactly how I prepare and send a 500-contact campaign:
- Prepare the Excel file. My file has four columns: phone number (international format with country code, no plus sign), first name, last name, and a tag column for segmentation. The phone number column is the only required one. Keep the file under 2MB — the system handles larger files via async import, but under 2MB uploads and processes instantly.
- Go to Campaigns in OT1-Pro and create a new WhatsApp campaign. Click the campaign type (WhatsApp), give it a name, and select the connected WhatsApp number you want to send from.
- Upload the Excel file and map columns. The import wizard shows you your column headers and lets you map them: "Column A → phone number", "Column B → firstname" and so on. This takes about 90 seconds.
- Write the message. I keep mine to 3–4 sentences. Use
{{firstname}}where you want the contact's first name inserted. The preview on the right shows exactly what the final message will look like for a sample contact. Keep it conversational — messages that read like a human wrote them have a 2–3x higher reply rate than ones that read like a marketing blast. - Set the schedule. You can send immediately or schedule for a specific time. I always schedule for mid-morning local time (10–11am) — reply rates are roughly 40% higher than evening sends for my audience.
- Review and confirm. The final screen shows contact count, estimated send duration (the system throttles sends to protect your account), and the message preview. Confirm and the system handles the rest.
The throttle system — why we slow sends intentionally
OT1-Pro sends campaigns with an intentional delay between messages. This is not a limitation — it is a feature that protects your WhatsApp number. Meta's spam detection system flags accounts that send hundreds of messages in a short burst to recipients who don't reply. By throttling the send rate and spacing messages over a period of time, the system keeps your delivery rate high and your account in good standing.
For a 500-contact campaign, the full send typically completes in 60–90 minutes depending on your plan tier. You can close the browser and the campaign continues in the background — you will get a notification when it is done.
Real results from a recent campaign
My most recent campaign: 500 contacts, a 15% discount code for a new collection launch.
| Metric | Result | Notes |
|---|---|---|
| Messages sent | 500 | Full list |
| Delivered | 479 (95.8%) | 21 undeliverable — wrong numbers, changed numbers |
| Read (blue ticks) | 412 (86%) | Sent 10:30am local time |
| Replied | 87 (18%) | Mostly "how do I order?" and "is size X available?" |
| Clicked or enquired about product | 114 (24%) | Includes replies + WhatsApp link clicks |
| Converted to purchase | 31 (6.5%) | Within 72 hours of campaign send |
| Revenue attributed | ~$2,015 | At $65 average order value |
| Campaign cost (plan tier) | $0 extra | Included in monthly plan limit |
Compare to my previous method — manually forwarding a promotion message to contacts one at a time from my phone. That got me maybe 20 sends per session before my thumb gave out. The campaign feature replaced that with a system I can run in 20 minutes.
Comparing the options: OT1-Pro vs WATI vs Respond.io
| Feature | OT1-Pro ($29/mo) | WATI ($39/mo) | Respond.io ($99/mo) |
|---|---|---|---|
| WhatsApp campaigns from Excel | ✓ All plans | ✓ Paid plans | ✓ Paid plans |
| Campaigns per month (Starter) | 5 | Unlimited (message credits) | Unlimited (message credits) |
| Personalisation placeholders | ✓ | ✓ | ✓ |
| Async import for large files | ✓ | ✓ | ✓ |
| AI inbox included | ✓ | ✗ | ✗ (separate product) |
| Comments + DM handling | ✓ | ✗ | Limited |
| Minimum contract | Monthly | Monthly | Monthly |
WATI's campaign feature is solid but their pricing model is message-credit-based, which means your effective cost scales with your list size. At 500 contacts per campaign run, the per-message cost adds up. OT1-Pro's plan limits (5 campaigns/mo on Starter, 25 on Pro) are designed for the typical small business that runs 2–4 major campaigns per month.
The plan limits and how to work within them
Campaign limits per month on each tier:
| Plan | Campaigns/month | Notes |
|---|---|---|
| Free | 1 | Good for testing the feature |
| Starter ($29/mo) | 5 | Enough for weekly campaigns |
| Pro ($79/mo) | 25 | Enough for daily campaigns |
| Business ($149/mo) | Unlimited | No cap |
If you are running 5 campaigns a month and hitting the Starter limit, the natural upgrade trigger is to Pro. The incremental cost ($50/mo) has to be measured against the revenue a few additional campaigns generate — in my experience, one extra campaign at 500 contacts converting at 6% at $65 AOV is $1,950 in revenue. The upgrade math is straightforward.
The 3 biggest mistakes to avoid
- Sending to cold lists. If the people on your list have never heard from you on WhatsApp, your reply rate will be near zero and your spam report rate will be high. Use campaigns for warm contacts only — people who have messaged you first, bought from you, or opted in explicitly.
- Sending at the wrong time. My data shows mid-morning (10–11am local time) consistently outperforms evening sends by 35–40% on reply rate. Test your own audience, but default to business hours if you don't have data yet.
- Writing like a marketing blast. "🎉 EXCLUSIVE OFFER! LIMITED TIME ONLY! GET 20% OFF NOW!" in WhatsApp format looks like spam and gets ignored. Write like you are sending a message from your personal number to a real customer. "Hey {{firstname}}, we just launched the new summer collection and given your past order history I thought you'd want early access — 15% off until Sunday." Same offer, different tone, dramatically different open and reply rate.
See the pricing page for full plan limits, or compare with WATI before deciding. Start free → and run your first test campaign on the Free plan before upgrading.
Try the AI inbox built for real businesses
OT1-Pro is the unified inbox I built to run my own operation: WhatsApp + Instagram + Messenger + Telegram + email, one screen, with an AI agent that replies in your brand voice and an integrated campaign tool for bulk WhatsApp and email sends. Free plan, no credit card →
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