Maintenance reminder emails: what heating contractors may send existing customers without new consent

It's September and you're going through your maintenance records: 38 customers are due in October. Instead of making 38 phone calls, you send them all the same email. The next morning, one of them replies: "Where did you get my address? I never agreed to this."

He's not entirely wrong. Legally, a maintenance reminder is almost always advertising, and in Germany advertising by email generally needs prior consent. § 7(3) of the German Act against Unfair Competition (UWG) makes an exception for existing customers. It comes with four conditions, and many businesses fail the last one before the first email even goes out.

This article covers the law in Germany. The rules in the rest of the EU, the UK and the US are further down. It is general information, not legal advice.

Is a maintenance reminder even advertising?

Germany's Federal Court of Justice (BGH) reads the term broadly. In its ruling of July 10, 2018 (VI ZR 225/17), advertising is "any statement made in the course of a trade, business, craft or profession with the aim of promoting the sale of goods or the provision of services". Crafts and trades are named right there in the definition.

The case was brought by a man who had bought a device through Amazon Marketplace. The seller emailed him the invoice and, in the same message, asked for a 5-star review. The local court and the regional court dismissed his claim for an injunction, but the BGH ruled for the buyer: asking for a review is advertising too, and having the legitimate invoice in the same email doesn't change that. The court threatened the seller with a fine of up to €250,000 for every further violation.

For your business, this means: "Your heating is due again, reply with a date that suits you" is meant to bring in a paid job. That falls under this definition of advertising, even if it feels like service to you and the customer gets something out of it.

Things are a little different with a maintenance contract in which the annual service is already agreed. Then you're arranging a date for a job the customer ordered long ago. There's a strong case that this isn't advertising, as long as the email sticks to scheduling. If you add an offer, say for a new burner, the logic of the Amazon case applies: the permitted part doesn't make the rest permitted.

The exception for existing customers: four conditions, all at once

§ 7(2) no. 2 UWG requires "prior express consent" for advertising by email. § 7(3) UWG makes an exception when all four points are met. The left column has the wording of the law, the right one what it means for a heating business.

The catch in no. 4

The notice in each email takes a minute to write. The hard part is the first point in time. If you noted the address on a job sheet in 2021 without a word about marketing or objecting, one condition is missing. Nothing in the law says you can make up for the notice later.

For older addresses like that, you have three options:

• Ask at the next service visit. A ticked box on the service report ("Yes, remind me of my next service by email") with date and signature is express consent you can prove.
• Send the reminder by letter. § 7(2) no. 2 names automated calling machines, fax and electronic mail, but not letters. For letters, the basic rule of subsection 1 applies: no advertising if it's clear that the recipient doesn't want it.
• Offer a maintenance contract. From then on you're arranging agreed dates, as described above.

And the phone: calling is stricter than emailing. Under § 7(2) no. 1 UWG, marketing calls to consumers need prior express consent, and the exception in subsection 3 only covers email. For business customers, at least presumed consent is enough. So with private customers who never gave consent, the 38 calls from the start wouldn't have been a way out either.

What belongs in every reminder

• Your business as a recognizable sender, in the sender name and in the signature. Under § 7(2) no. 3(a) UWG, advertising that conceals the sender's identity is always prohibited.
• A valid address the customer can write to and say they don't want anything more (no. 3(c)). The simplest is the email's reply address, as long as someone actually reads what arrives there.
• The opt-out notice with everything subsection 3 no. 4 lists: at any time, and without costs other than the transmission costs at the basic rates.
• A separate paragraph for this notice. Art. 21(4) GDPR requires the right to object to be "presented clearly and separately from any other information". Small grey text tucked into the signature doesn't meet that.
• Only the similar service. A maintenance reminder is no excuse to pitch bathroom renovations and solar panels on the side.

Templates

The templates use a polite, formal tone. Adjust the company name, contact details and service.

Notice when you collect the address

Put it on the order confirmation, the service report or the booking form on your website, in other words wherever you first get the email address:

We use your email address to remind you of your heating system's next service and to offer you similar services from our business. You can object to this at any time, by email to [email address] or through the unsubscribe link in every email we send. You will not incur any costs for this other than the transmission costs at the basic rates.

The reminder

Subject: Your heating is due for its service in November

Hello,

The annual service for your heating system is due again in November. Just reply to this email with two or three days that suit you, and let us know whether mornings or afternoons work better. We will then confirm the appointment.

Best regards
[Name], [Company]
[Address], [Phone]

You are receiving this email because you hired us for work on your heating system. If you no longer want reminders by email, you can object at any time: through the unsubscribe link below or with a short reply to this email. You will not incur any costs for this other than the transmission costs at the basic rates.

Keep the last paragraph even if the customer has already had 10 reminders. "Each time it is used" means each time.

When a customer objects

Hello Mr. Kaya, done: you won't receive any more reminders or offers from us by email. If your heating ever needs help, you can reach us as usual at [phone]. Best regards, [Name]

How to send the reminders every month with Deskwoot

Deskwoot is a shared inbox for email, WhatsApp, live chat and other channels. Email campaigns and custom contact attributes come with the Business plan and up. Here's what the process looks like for a heating business:

1. Under Settings > Custom Attributes, an administrator creates a contact attribute called "Maintenance month" of type List, with the 12 months as options. A second list attribute, "Email marketing", with the values "Notice given", "Consent" and "Objected", records who said what. Your team sees both on the contact and to the right of every conversation with that customer. Customers don't see them.
2. You enter the values on the contact in the Attributes tab, using the pencil icon. For your whole customer base, an administrator can use the CSV import under Settings > Import & Migration: name the column after the attribute's key, and existing contacts with the same email address get updated. Spell the months exactly as they appear in the list.
3. Once a month, go to Campaigns and create a new campaign of type One-off, with your email inbox as the sender and Specific contacts as the audience. Paste the reminder from the template as the message. Campaigns don't insert names, so everyone gets the same text, which is why the template opens with just "Hello,". Search for the customers who are due by name or email and add them. You'll see who's due in your maintenance records or your job management software, because Deskwoot doesn't filter contacts by attribute, and custom segments don't look at attributes. Leave out customers marked "Objected".
4. Pick the send date and time in steps of 15 minutes, for example the first Tuesday of the month before at 8 a.m., and activate the campaign.

With 38 customers due, that's 38 searches in the form. For a business with a few dozen services a month, that works. If you send several hundred reminders a month, you'll want the selection pulled automatically from your job management software, and Deskwoot can't do that today.

Below every campaign email, Deskwoot adds a line saying why the contact is getting it, plus an unsubscribe link. It also adds the headers that let email programs offer unsubscribing with a single click. Anyone who unsubscribes through the link shows as "Unsubscribed from campaigns" on their contact and gets no more campaigns, even if you select them by mistake. Deskwoot also skips blocked contacts, contacts without an email address and addresses that bounced permanently. Customers who object by reply or on the phone, however, are not unsubscribed in Deskwoot. Set "Objected" for them and cross them off in the records you pick from each month too. The automatic line doesn't replace your opt-out notice, though, because it doesn't mention the costs. So put the notice in your own text, as in the template above.

When a customer replies with dates that suit them, the reply lands as a normal email in the conversation in your inbox, with the maintenance month right next to it. Whoever in the office has a moment confirms the appointment there.

On Business, only administrators can send and activate campaigns. Your office staff prepares the draft and you send it off. On Enterprise, you can grant this permission through a custom role. The individual steps are in the help articles on campaigns and custom attributes.

Business costs $8 per agent per month, or $6.40 with annual billing. If two people in your office write to customers, that's $12.80 a month with annual billing. You can try it free for 7 days, no credit card needed. The trial includes everything in Enterprise, so campaigns are part of it. There's more on Deskwoot for the trades on the page for trades businesses, and all plans are on the pricing page.

Outside Germany

§ 7 UWG is German law. In the ruling cited above, the BGH writes that the legislature used it to implement Art. 13 of EU Directive 2002/58/EC. The other EU countries implemented the same directive in their own laws, with their own wording and their own case law. So check the rules in your country.

In the UK, the exception is called the "soft opt-in". According to the data protection authority, the ICO, negotiating a purchase is already enough there to meet the first condition. The ICO itself points out that it is revising its guidance because of the Data (Use and Access) Act.

In the US, the CAN-SPAM Act doesn't require prior consent for marketing emails, according to the FTC's compliance guide. You have to honor opt-outs within 10 business days, and the way to opt out must keep working for at least 30 days after you send. Purely transactional messages are exempt from most of the rules, but according to the FTC the law reads that exemption narrowly. Other countries have their own rules as well.

What you can do this week

Add the notice to your order confirmation and your service report. It costs nothing. Every address you get from then on meets no. 4 from the start, no matter which software you use for the reminders later.

This article is general information, not legal advice. The provisions cited are as of October 2026.