Add Reply-To header support to the Mailspring composer

Plugins
1

mailspring-reply-to-from

A Mailspring plugin that adds a Reply-To field to the email composer.

Mailspring has no built-in UI for setting a Reply-To header when composing emails. This plugin adds a :right_arrow_curving_left: Reply-To button to the composer toolbar that lets you set one with a single click.

Installing

  1. Grab the latest release

  2. Extract the zip somewhere

  3. From the Mailspring menu, select Developer > Install a Plugin.... In the dialog, choose the folder that was extracted from the zip file to install the plugin

  4. Reopen Mailspring

Usage

  1. Open a new compose window

  2. Click the :right_arrow_curving_left: Reply-To button in the bottom toolbar

  3. Type the reply-to address

  4. Press Save BTN or hit Enter

The button label updates to show the current Reply-To address so you can see at a glance when one is set. Click it again to change or clear it.

How it works

Mailspring’s Message model already has a replyTo field — it just isn’t exposed in the composer UI. This plugin writes to that field via the draft session, which Mailspring’s sync engine then includes as a Reply-To: header when the message is sent.

No build step or npm install required. The plugin is plain JavaScript.

Contributing

PRs and issues welcome! If Mailspring exposes a proper header injection slot in a future version, the goal would be to migrate to a native inline field row (like Cc/Bcc) rather than a toolbar button.

Specify Reply-To header when composing
2

I’ve made a pull request to add this to native UI nicely)