Email templates#

Address type	Regular e-mail address.
Default gateway	Your SMTP server. Or your ISP’s. Or 3^rd-party ones.
Encoding	ASCII
Content type	HTML and/or plain text.
Maximum content length	Several MegaBytes.
Emojis	Yes.
Costs	None.

Read SMS templates first as this builds upon it.

An email has multiple parts at play:

a subject
a body
potentially a HTML version of the body
potentially a priority

Email templates collect each of those parts in a separate template file. All such files are enclosed into an email folder:

templates_base/
└── mywebapp/                       <-- a scope
    └── password_changed/           <- an event
        └── email/                  <- email vector
            ├── subject.txt         <- mandatory
            ├── body.txt            <- mandatory
            ├── body.html
            └── priority.txt

Hint

The body.txt definition is not required in Tattler’s enterprise edition.

Tattler enterprise edition includes the auto-text feature, which allows you to only provide body.html.

The files have the following purpose:

subject.txt: Mandatory. Contains template text which will be expanded with template variables to generate the subject of the email to send.
body.txt: Mandatory (in Tattler community edition). Contains template text which will be expanded with template variables to generate the body of the email to send. This is the plain-text body standard in every email. If a body.html file is also provided, this content only serves as a “fallback” for recipients who lack support for HTML emails.
body.html: Optional. Contains template text which will be expanded with template variables to generate the HTML version of the email to send. If the recipient’s e-mail application supports HTML emails, they will view this content first.
priority.txt: Optional. Contains an integer ∈ { 1, 2, 3, 4, 5 }, where 1 is “highest” and 3 is “normal” priority. Priority is implemented by setting the X-Priotity header in the final email to the user, so its potency depends on whether the user’s email application supports that attribute – which many do.

HTML Emails#

HTML emails are plain-text emails with an HTML file attached, packaged in a special way dictated by the MIME standard.

Tattler takes care of this special packaging, so your job is to write the template for that HTML file.

Write the HTML template into file body.html. Make it valid HTML enclosed in a <html></html> element:

<!-- this is the content of file body.html -->
<html>
    <body>
        <h1>Password changed!</h1>

        <p>Dear {{ user_firstname }},</p>

        <p>Someone (presumably you) changed the password to your account today at  {{ appointment_time }}.</p>
    </body>
</html>

Hold your HTML#

Tattler supports all the HTML you want, but email clients don’t.

Some email clients don’t support HTML at all – in which case your recipient will only see the content you prepared in body.txt.

Clients that do support HTML emails do so limitedly and inconsistently.

Avoid JavaScript. Basic CSS is often supported. Refer to the excellent CanIEmail.

Email priority#

Many email clients support setting and viewing an email priority.

These include Thunderbird, Gmail, Outlook and Apple mail.

tattler allows you to set an email’s priority by placing the priority.txt file into the email template folder:

cd templates_base/password_changed/email/
echo "1" > priority.txt

This will make the message “high-priority” when the user’s email application supports the feature.

Setting this file makes sense with only 2 values:

1 for “high priority”
5 for “low priority”

Value 3 (normal priority) is a non-action, and the values in-between are not meaningful.

Setting messages as high-priority raises the visibility of the notification in the user’s mailbox, which loads notification fatigue even further – so use it sparingly. A case where high-priority makes sense is when the notification is important and also time-critical action.