SMS vs email vs letter: what actually gets boiler services booked?

Email is the workhorse. It's effectively free per message, you've got room to actually explain what's due and why, and you can put a clear booking link that opens straight into a calendar. The catch is that inboxes are busy - a reminder can get buried under promotions and Amazon updates within a couple of hours. The saving grace for service reminders is that the sender is a known tradesperson the customer has used before, so open rates on this kind of email are typically much better than cold marketing email. The customer isn't being sold to - they're being reminded about their own boiler.

SMS is the nudge that gets seen. Text open rates are near-universal and usually within minutes, which makes SMS perfect for a follow-up when an email hasn't landed. The trade-offs: it costs pence per message rather than nothing, and you have to keep it short - one clear sentence and a link, no essay. It's a poor fit as the only channel because you can't include much context, but it's an excellent second touch.

Letter is the channel most trades have quietly retired. Print, paper, envelope, stamp, walk to the postbox - the cost per contact is enormous compared to email or SMS, and the response is typically no better and often worse because there's no clickable booking link. It still has a narrow role for older customer bases who genuinely prefer post, and for compliance-critical notices where you want a physical paper trail. For most gas engineers today it isn't worth the effort.

The phone call is the forgotten channel. Conversion is the highest of the lot because you're speaking to a human and you can agree a slot on the spot. It also costs your evening. Ringing 150 customers a year, twice each if the first attempt didn't answer, is a real time sink - and it's the reason most trades never actually do it consistently. Software exists precisely because that manual loop breaks the first time you have a busy week.

Pick any channel. If the message says 'your boiler service is due, ring us to book', you'll lose most respondents no matter what. The customer means to call, they get distracted, the reminder falls off the mental to-do list, and by the time they remember they're Googling a stranger. The conversion step is the booking link, not the channel.

The pattern that actually gets jobs in the diary is the reminder-to-confirmed-booking loop: a reminder that includes a one-tap link the customer can open, pick a slot from, and confirm - right then, on their phone, without speaking to anyone. When they tap the slot, the job lands in your diary as a confirmed booking. That's the difference between a channel that generates messages and a channel that generates work. For a longer definition, see our page on rebooking software for UK trades.

Everything in this article about SMS versus email is downstream of that. The channel decides how likely the reminder is to be seen. The booking link decides how likely a seen reminder is to become a booked job.

For most UK gas engineers, the pattern that recovers the most repeat work with the least friction is email first, SMS chaser only if there's no response. Email carries the explanation and the booking link. If the customer hasn't clicked or booked a few days later, a short SMS follows up: one sentence, same booking link. If they still haven't responded closer to the due date, one final SMS nudge is worth sending on paid plans.

That's the default Bookso automates: email on day zero with the booking link, an email chaser a few days later if there's been no response, and one SMS nudge around day seven for paid tiers if the customer still hasn't booked and hasn't opted out. It's automatic escalation only - Bookso doesn't have a manual 'text this customer' button because the loop works best when it runs itself.

For most books of customers, this three-touch pattern lands most bookings on the first email, mops up the forgetters with the chaser, and catches the last few with the SMS. Nobody has to phone anybody.

Email is effectively free per message. There's a cost to running the platform that sends them, but per-reminder it's rounding-error territory.

UK SMS costs a few pence per message on most providers. In practice, a solo gas engineer with a couple of hundred active customers sends dozens rather than hundreds of texts a month, because SMS is the chaser rather than the first touch. On Bookso, the Pro plan at £14.99/month includes 75 SMS a month and Business at £44.99/month includes 250 - enough for the vast majority of solo and small-team gas engineers without ever needing to top up.

The maths only has to work in one direction. A single recovered £85 boiler service more than covers a month of the software, including the SMS. Recover two and you're comfortably ahead every month. If you want to see how quickly that adds up across a year of missed rebookings, we walked through a transparent model of the yearly leak in our earlier post on how much repeat work UK tradespeople lose by never rebooking - the same arithmetic applies whether you're on Pro or Business.

For a full breakdown of what's included at each tier, see Bookso pricing.