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Translated from German; if the versions differ, the German version applies.
Not legal advice: Legal content on this page appears only as verbatim quotations from statutes, court rulings or authority papers, with their source; quotations from German texts are our working translations. We do not assess them ourselves, and no lawyer has reviewed this page. It is no substitute for legal advice in your individual case.
Subject line and preview text
In the inbox, readers first see three things: the sender name, the subject line and – in many programs – a line of preview text. Whether someone opens an email is decided in these three places. This page explains what belongs in each, what the law and mailbox providers say about it and how to compare subject lines without being misled by unreliable figures.
What a good subject line does
A subject line says what this issue is about – not that a newsletter exists. “Newsletter October” tells the reader nothing; “New opening hours from 1 November and three autumn dates” does. In our work, the following has proved useful:
- Put the most important point first. How many characters a mailbox displays depends on the program, the device and the window width. Whatever comes first is almost always read.
- Concrete words instead of advertising language. A date, a place, a number, a topic – this helps readers decide and helps them find the email later with their mailbox search.
- One message per subject line. Announcing five topics announces none of them properly. Further topics belong in the preview text or in the email.
- Stay recognisable. A fixed element (such as the name of the series) helps regular readers without pushing out the actual content.
Preview text (preheader)
Many mail programs show the beginning of the email text below or next to the subject. If that line reads “If this email is not displayed correctly …”, it is wasted. Most sending platforms therefore offer a separate field for preview text: a short line placed at the very top of the text that complements the subject line instead of repeating it.
| Subject line | Preview text that complements it |
|---|---|
| New opening hours from 1 November | Saturdays now until 16:00 – and three autumn dates for your diary |
| Your tax return guide is here | Twelve pages, ready to print, with a checklist at the end |
Preview text is no substitute for a clear subject line: not every program shows it, and some shorten it considerably.
What the law and mailbox providers say
The law. Section 6(2) of the Digitale-Dienste-Gesetz (DDG, the German act on digital services) reads as follows. Quotations from German laws are our working translations; only the German wording is authoritative (see the German version of this page).
“Where commercial communications are sent by electronic mail, neither the sender nor the commercial nature of the message may be disguised or concealed in the header and in the subject line. Disguising or concealing exists where the header or the subject line is deliberately designed in such a way that the recipient, before viewing the content of the communication, receives no information or misleading information about the actual identity of the sender or the commercial nature of the message.” (our translation) — Section 6(2) DDG
Section 6(1) DDG reads: “When making commercial communications that are digital services or components of digital services, service providers must at least observe that […] commercial communications must be clearly recognisable as such” (Section 6(1) no. 1 DDG, our translation). Section 5a(4) sentence 1 of the German Act against Unfair Competition (UWG) reads: “A person also acts unfairly who does not make the commercial purpose of a commercial practice recognisable, unless it is immediately apparent from the circumstances, and where not making it recognisable is likely to cause the consumer or other market participant to take a transactional decision that they would not otherwise have taken.” (Section 5a(4) sentence 1 UWG, our translation)
Which subject lines fall under this in detail, and whether a note on advertising must appear in the subject line, is not expressly answered by the law. The wording in context: Sender, subject line, labelling, unsubscribing.
No false “Re:” and “Fwd:”. In its Email sender guidelines, Gmail requires subject lines to start with “Re:” or “Fwd:” only if the message really is a reply or forward, and headers and content must not be misleading.
Keep the sender name clean. According to the same guidelines, the display name should not contain the recipient’s name, the subject or message content, or emojis or special characters that imitate graphic elements.
Emojis, umlauts and special characters
Email header fields originally consisted only of ASCII characters. Umlauts, emojis and other characters in the subject line are therefore packed as so-called “encoded words” under RFC 2047 (format =?UTF-8?B?…?=); your sending platform takes care of this. Whether an emoji appears in colour, in black and white or as an empty box depends on the program and the device. Before sending, therefore, send a test issue to mailboxes at several providers and on both phone and computer.
For screen readers: an emoji is usually read out by its name. Three emojis in a row then sound like a long, incomprehensible start to a sentence. Use emojis sparingly, if at all, and not in place of words.
Testing subject lines
Comparing two subject lines (A/B test) is tempting, but there is a catch: the obvious measure, the open rate, is unreliable today. With “Protect Mail Activity”, Apple Mail loads remote content privately in the background as soon as an email arrives – to the sender, this looks like an open. It is therefore better to compare subject lines by clicks or by what happens afterwards. How a fair test is set up and when a difference is more than chance is explained on A/B testing in newsletters.
Subject line checklist
- Does the subject line say what this issue is about?
- Is the most important point at the start?
- Does the preview text complement the subject line instead of repeating it?
- Does the subject line start with “Re:” or “Fwd:” only if it really is a reply or forward (Gmail sender guidelines)?
- Is the sender name recognisable and free of subject, recipient names and substitute graphics?
- Checked in a test send: display on phone and computer, at several mailbox providers?