Somewhere between "booking confirmed" and "see you at the dock," your guests forget everything.
The time. The location. What to bring. You know this because they email you the night before to ask.
Here's how to automate sending the answer 48 hours before the question arrives.
Note: This workflow uses YAMM, a free Gmail add-on that sends a personalized version of any email to every guest on a Google Sheet — their name, dive date, location, and gear list filled in automatically.
If you want tips for how to do this in Microsoft 365, reply to this email.
First, build your guest roster in Google Sheets
Create a new Google Sheet and add these column headers in row 1. The exact spelling matters — you'll reference them in the template.
Column | What goes in it |
|---|---|
First Name | Guest's first name |
Email Address | Their email |
Dive Date | The date of their dive (e.g., June 20) |
Arrival Time | When to arrive (e.g., 7:30am) |
Departure Time | When the boat leaves (e.g., 8:00am) |
Meeting Point | Dock name or address |
Maps Link | A Google Maps URL for the meeting point |
One row per guest. Each email is personalized with the column headers.
Second, install YAMM
YAMM is free to install from the Google Workspace Marketplace. You only do this once.
Open Gmail in a browser
Click the grid icon (top-right, next to your account avatar) → "More Google apps" → search "YAMM"
Click Yet Another Mail Merge → Install → approve the permissions
Open the Google Marketplace from inside Gmail
Search for YAMM, click to install it, and a YAMM icon will appear in your Gmail toolbar
Third, write your briefing template
See this guide with screenshots on creating a reusable template for free in Gmail.
Open a Gmail compose window and write your pre-trip email.
Anywhere you want to insert a guest's specific detail, type the column name from your Google Sheet (image above) wrapped in double curly braces.
YAMM replaces every {{}} variable with the matching value for that guest in the sheet
Do not send this email — leave it as a draft, or keep the compose window open.
Fourth, send the merge
Click the YAMM icon in your Gmail toolbar (or open it from the Extensions menu)
Under Select a spreadsheet, choose your guest roster sheet
Select the correct tab (e.g., "June 20 Morning Two-Tank Dive")
Click Receive a test email — YAMM sends the first row to you so you can check how it looks
Review the test. If the merge fields populated correctly and the formatting looks right, click Send emails
YAMM sends each guest a separate, personalized email from your Gmail address. Replies come back to you.
What else you can send with this setup
Once you have a Sheets roster and YAMM installed, every email that goes to a group of guests becomes a merge:
What to send | When | What to personalize |
|---|---|---|
Pre-trip briefing | 48 hours before | Name, date, time, location, gear list |
Day-of check-in reminder | Morning of | Name, departure time, dock location |
Certification card reminder | 1 week before | Name, dive date, cert type required |
Post-trip review request | Day after | Name, dive site, guide's name |
Season re-engagement | Off-season | Name, last dive date, current offers |
Rescheduling offer | After a cancellation | Name, alternative dates |
Three things that catch people out
The 20/day ceiling. YAMM's free plan sends to 20 recipients per day across all merges. A 20-person boat plus two test emails puts you at the limit. The fix: YAMM Pro at $25/year raises it to 400/day. For most small shops sending one briefing per trip, free is enough — until it isn't.
Column names must match exactly.
{{First Name}}works if your column is called "First Name." If you typed "firstname" or "First name" (lowercase n), the merge field won't resolve and your guests receive the literal text{{First Name}}. Check column headers before you send, especially after copying a Sheet from a previous trip.Keep a per-trip tab, not one master sheet. The cleanest habit: for each upcoming trip, copy your column headers into a new tab named by date ("June 20"), paste that trip's guests, run the merge, then archive the tab. This prevents accidentally sending to all guests across all dates when you only meant to brief tomorrow's group.
What trip detail do your guests most often miss — wrong dock, wrong time, or showing up without their cert card? Reply and tell me because I'm building another issue to automate fixes for the most common pre-dive confusion.
- Dave
P.S. YAMM's free tier resets at midnight Pacific. If you run two trips in one day and both have 10 guests, send the morning trip's briefing before midnight the night before.
Sample Pre-Trip Briefing Email to Automate
Hi {{First Name}},
Here's everything you need for your dive on {{Dive Date}}:
WHEN AND WHERE
Arrive by {{Arrival Time}} — we leave at {{Departure Time}} sharp.
Meet us at: {{Meeting Point}}
Directions: {{Maps Link}}
WHAT TO BRING
— Certification card (photo on your phone is fine)
— Government-issued photo ID
— Swimsuit or wetsuit (rentals available — reply if you need one and tell me your size)
— Towel
— Water and snacks for the surface interval
— Any prescription meds you take before diving
— Cash or card if your balance isn't settled yet
SUNSCREEN
Reef-safe only — no oxybenzone or octinoxate.
We sell it at the shop if you need some. Mineral-based is best.
LEAVE BEHIND
Phones, cameras, and valuables stay in the car or at the shop.
No secure storage on the boat.
One thing worth knowing: if you haven't dived in more than 12 months,
let me know when you arrive. We'll do a quick refresher in the shallows
before the main dive — no charge.
Any questions before {{Dive Date}}, just reply here.
See you at the dock,
[Your Name]
[Shop Name]
[WhatsApp number for day-of contact]