How a mailto link is structured
A mailto link is a URL that tells the browser to open the default mail client with fields pre-filled. The address goes straight after mailto:, and everything else travels as query parameters: subject, body, cc and bcc. Multiple recipients are separated by commas. Because it is a URL, any character that is not URL-safe has to be percent-encoded.
mailto:hello@yourdomain.com?cc=team@yourdomain.com&subject=Quick%20question&body=Hi%2C%0A%0AI%20saw%20your%20postSpaces become %20, line breaks become %0A, and characters like ampersands, question marks and commas inside text must be encoded so they are not mistaken for URL syntax. This generator uses the same encoding browsers expect, so what you paste is what the client shows.
Where mailto links earn their keep in outbound
Cold email itself rarely needs a mailto link, because the recipient can simply reply. Where they shine is everywhere around the campaign: the contact button on your landing page, a reply-with-template link in a case study, a referral ask in a newsletter, or a support address in an app. A pre-filled subject line makes replies easy to route and lets you spot which asset generated the email.
- Pre-fill a subject like Intro request from pricing page so replies are easy to filter.
- Keep the body to a short template with blanks; prospects finish it in their own words.
- Use a role address on a domain that has SPF, DKIM and DMARC, since replies will come in there.
- Avoid stuffing long legal text into the body; it inflates the URL and looks spammy.
Limits and gotchas
There is no formal length limit for mailto links, but browsers and mail clients truncate silently at different points, and very long bodies can be cut off or dropped entirely. Staying under roughly two thousand encoded characters is safe across desktop and mobile clients. Bodies are plain text only: HTML tags appear literally, and formatting like bold is not supported.
Bear in mind that a mailto link exposes every address, including BCC, in the page source. Scrapers harvest these, so a public mailto to your primary sending domain can attract spam. Use a role address or a contact form for high-traffic pages, and keep the domains you use for outreach out of public links where possible.
