What is quoted-printable encoding?

Quoted-printable encoding is a way to send text that's mostly readable ASCII characters with a few special characters mixed in (think accents, non-English letters, or symbols). Instead of encoding the entire message in Base64 (which makes everything unreadable), quoted-printable only encodes the weird characters and leaves the rest alone.

Here's how it works. When an email contains a character that isn't plain ASCII (like é or ñ or €), quoted-printable converts it to an equals sign followed by two hexadecimal digits. For example, the é in "café" becomes =E9, so the word looks like caf=E9 in the encoded version. Everything else stays readable.

Why does this matter? Because email was originally designed for plain ASCII text. When you send characters outside that range, the email system needs a way to preserve them without breaking. Quoted-printable is the encoding method that keeps most of your text human-readable in the raw source while safely encoding the special characters.

You'll see quoted-printable encoding declared in email headers like this:

Content-Transfer-Encoding: quoted-printable

The alternative is Base64, which encodes everything (even plain text) into a block of random-looking characters. Base64 is more efficient for images or attachments, but quoted-printable is better for text that's mostly English or ASCII-based with occasional special characters.

But when does this come up? If you're sending emails with accented names, international characters, or certain symbols, your ESP or mail server automatically chooses quoted-printable encoding. You don't usually configure this yourself. It just happens in the background. But if you're debugging an email that looks garbled or you're inspecting raw email source, understanding quoted-printable helps you decode what you're seeing.

Most ESPs (Mailchimp, SendGrid, Postmark) handle this automatically. You won't need to think about it unless you're building a custom SMTP setup or troubleshooting raw email source. If you're curious what your emails look like under the hood, try our Email Source Analyzer to inspect the full headers and encoding.