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OpenIn 4

Documentation - 03. Mail apps

Table of content

Mail apps

Mail apps


If you aren’t planning to use OpenIn for handling mailto: links on your Mac, you can disable it completely, so OpenIn will not try to check if other apps are set as default for handling Web links.


Remove all applications

OpenIn automatically discovers applications that can be used as Mail Apps on your system. You can remove all applications and rebuild the list on your own.

Add application…

OpenIn shows a dialog with all the applications that can be used as Mail Apps found on your system, if you are planning to rewrite the URL to a different scheme, or use the Browser with the Web Mail App, you can add it here.

Select applications from the Add applications list and press Add to add them to the list of the applications for the Mail Apps.

You can add the same application more than once, that helps for example to configure them differently. For example, to use the same browser but with different Web Mail sites.

Order of the applications

OpenIn uses the defined order of the applications, when it shows the App Selection menu, when you click the link. You can change the order by dragging applications by .

Edit application

Edit applications

Edit applications

Based on the type of the application, you might see slightly different configurations.

  • Name - you can give any name to the application, it does not change the name of the app on the system.
  • Icon overlay - you can add an icon overlay, this is useful if you, for example, add the same browser or application with different configurations

Safari and Firefox Private Mode

Please read information how to configure Safari Private Mode in the Browsers section

Chromium profiles

Please read information how to configure Chromium Profiles in the Browsers section

URL Rewrite

If you have added application that does not support mailto: scheme, you need to rewrite the URL to a supported scheme. You will see a warning if you aren’t rewriting URL, and OpenIn discovered that editing application does not support mailto: scheme.

You can rewrite URLs with JavaScript. Click Edit script… button to modify the script.

OpenIn provides two examples how to rewrite mailto: link to the https:// link to open with the Browser for Google Mail and FastMail.

For learning more about what objects are available, please read 07. JavaScript Editor for Apps.

How to configure OpenIn to use other email services as a Mail Application?

You need to find a correct url that will allow to compose a new message. In this URL you need to find a way to pass to, subject, body, cc and bcc as parameters. The most important is to.

Launch Configurations

You can configure how OpenIn launches the application

  • New instance - Whether you want the system to launch a new instance of the app. For Chromium browsers to be able to open a URL in a specific profile, we always need to launch a new instance of the browser. The same for Safari In Private mode.
  • Adds To Recent Items - Whether to add the app or documents to the Recent Items menu, if application supports that.
  • Activates - Whether the system activates the app and brings it to the foreground. You can uncheck that to launch URL in background.
  • Hides - Whether you want the app to hide itself after it launches.
  • Hides Others - Whether you want to hide all apps except the one that launched.


Rules help you to organize how OpenIn uses selected applications. If no rules are defined, it will show the selected apps in the App Selection menu, when you click the mailto: link. Similar if no rules match conditions, OpenIn will just show the list of the applications from above.

In the list you can edit or remove rules.

Order of the rules

Order of the rules matters. OpenIn goes from first rule of the list to next one, and verifying if the conditions are met. The first that matches conditions will be executed. You can change the order of the rules by dragging .

Edit rule

Edit Rule

Edit Rule

You can configure the Name of the Rule to help you identify it. If you aren’t satisfied with the rule yet, you can Disable it, while trying to figure out what works best for you.


You have several conditions to configure. If you have specified multiple conditions they will work as AND, except multiple domains matches and multiple sent from apps are executed as OR in those lists.

Execute when

  • With key Modifiers - you can configure this rule to execute only when those key modifiers are pressed, when you click the link.

Execute with Focus

OpenIn can be configured based on the selection of System Focus. OpenIn cannot read which focus is set, but you can configure Focus Hints parameters that you can use with the Focus editor in the System Settings. And when Focus Hint matches the one configured in the rule, this rule will be executed.

To learn more, please review Tutorial: Configuring rules based on the Focus selected in macOS system.

Matches domains

You can add one or more domain matches. In case if you configured multiple domains just one of them needs to be matched. Use * for matching.


    • * matches both and

Sent from apps

You can configure the to execute this rule only when mailto: link is sent from specific application. In case if you configured multiple applications in this list, just one of them needs to be matched.

Use applications

You can configure how this Rule shows applications defined for in the list of applications.

  • All - all applications from the list will be used
  • All (running) - only running applications will be showed. If none of the applications are running, this rule is skipped.
  • Selected - only applications that you have selected in the list will be used.
  • Selected (running) - only running applications, that you have selected in the list will be used. If none of the applications are running, this rule will be skipped.

Custom script

You can define you custom JavaScript to change the URLs or select the Mail apps on your own custom condition.

For learning more about what objects are available, please read 08. JavaScript Editor for Rules.

Example: how author of OpenIn uses the OpenIn

The list of applications I have:

  • Mail - standard instance without any changes in the configurations.
  • Chrome (OS) - Chrome browser with configured work profile and rewrite rule for GMail.
  • Fastmail - Safari browser with rewrite rule to use FastMail as web email client

In the rules I have next set of rules

  • Cmd - With Key Modifiers and All apps.
  • Default - My default rule with only one Mail app.

With this configuration in most cases my mailto: links are opened in, and when I press I have the selection of all Mail apps defined.