Revenue per send: the email metric venues should track
Revenue per send measures the actual financial return of an email campaign by connecting sends to return visits and spend at a physical venue. This guide explains why it beats open rate as a metric, how Purple Engage calculates it automatically using guest WiFi data, and how marketing directors and CRM managers can act on it this quarter.
Why this matters for your venue
Open rates and click-through rates are proxy metrics. They tell you if someone looked at your message, but they do not tell you if that person walked through your door and spent money. For a physical venue, the only metric that truly matters is revenue per email.
The cost of ignoring this is real. Generic email tools like Mailchimp or Klaviyo send the campaign, but they do not build the list. More importantly, they cannot close the loop. If you send 10,000 emails offering a half-price appetizer, a standard tool reports a 20% open rate. It will not tell you how many of those 2,000 people actually visited your restaurant, logged into your WiFi, and spent £50 on dinner.
Revenue per send changes the conversation from "did they like the email?" to "did the email drive revenue?" For a marketing director defending budget in a board meeting, that is the only conversation worth having.
The approach
Revenue per send connects the digital action (sending an email) to the physical outcome (a visit and a transaction). The mechanism relies on a single, continuous thread of identity.
When a guest visits your venue and logs into the guest WiFi, they provide their email address. This is conscious-choice, first-party data, fully compliant with GDPR. Purple captures this data and builds your customer list automatically. When you send a campaign through Purple Engage, the system tracks who received it. When that guest returns and their device reconnects to the WiFi, Purple registers the visit. By applying an average spend per head, you calculate the exact revenue generated by the campaign.
This is not an estimate. It is a verified number, grounded in real network authentication data from 80,000+ live venues and 440 million logins in 2024 (Purple internal data).
| Metric | What it measures | What it misses |
|---|---|---|
| Open rate | Did the guest see the email? | Whether they visited |
| Click-through rate | Did the guest engage digitally? | Whether they spent money |
| Revenue per send | Did the email drive a visit and revenue? | Nothing - this is the complete picture |
How to do it with your guest WiFi
Purple Engage automates this entire process. The customer list builds itself from guest WiFi logins.
First, configure the captive portal. This is the login screen guests see when connecting to the network. Set the authentication method to require an email address, ensuring you capture verified, first-party data with a clear GDPR consent checkbox.
Next, build the campaign in Purple Engage. Define the audience using the data collected via the WiFi network. Target guests who have not visited in 90 days, or those who consistently visit on Tuesday afternoons.
Finally, deploy the campaign. Because Purple sits at the network layer, it monitors return visits automatically. When a targeted guest walks back into the venue, their device authenticates on the network. Purple logs the return visit, attributes it to the specific campaign, and calculates the email campaign revenue.
Purple integrates with Cisco Meraki, HPE Aruba, Ruckus, Juniper Mist, Ubiquiti UniFi, Cambium, Extreme, and Fortinet hardware, so you do not need to replace your existing infrastructure.
What to send, and when
Timing and segmentation are critical. Sending the same email to your entire database dilutes your email revenue per send. Segment your audience based on their physical behaviour.
The Lapsed Guest: Target guests who have not visited in 60 days with a strong incentive to return. A discount, a free item, or an exclusive experience. The goal is to get them back through the door.
The Regular: Reward frequent visitors with exclusive offers or early access to events. Do not waste a discount on someone who was going to visit anyway.
The Event Attendee: Send follow-up campaigns to guests who logged in during a specific event or promotion. They have already shown interest in that type of experience.
Automations ensure these messages reach the guest at the right moment. Trigger an email 24 hours after a guest's first visit, thanking them and offering a discount on their next purchase. Trigger a re-engagement email if a regular guest has not been seen in 30 days. For more on building these segments, see our guide on Using dwell time and visit data to segment venue guests.
Measuring what works
To measure email ROI accurately, establish a baseline average spend per head for your venue. If you operate a pub, this might be £15. If you operate a hotel, it might be £150.
Once you have this baseline, the calculation is straightforward. If a campaign goes to 1,000 people, 50 of those people return within 14 days of the send, and your average spend is £20, the campaign generated £1,000 in revenue. The revenue per send is £1.00.
This metric allows you to compare campaigns objectively. A campaign with a 15% open rate but a £1.50 revenue per send is significantly more valuable than a campaign with a 30% open rate but a £0.20 revenue per send.
One important note on attribution windows: for most venues, a 14 to 21-day window is the right balance. Too short and you miss delayed conversions. Too long and you attribute visits that had nothing to do with the campaign.
Where to start
- Audit your captive portal. Ensure your guest WiFi requires an email address for authentication and includes clear GDPR consent language.
- Establish your baseline. Determine the average spend per head for your venue, by daypart if your spend varies significantly.
- Define your segments. Create distinct audiences in Purple Engage based on visit frequency and recency. Start with lapsed guests - they have the most to gain.
- Launch a test campaign. Target a specific segment with a clear, single offer. Keep the creative simple.
- Track the return visits. Use Purple Engage to monitor how many recipients return to the venue within your attribution window.
- Calculate and report. Divide total attributed revenue by total emails sent. Present this number alongside open rate in your next campaign report.
For more details on setting up your network to capture this data, review our guest WiFi capabilities and explore the full feature set of Purple Engage.