4. Composing & Sending

1. The Postbox Interface
2. Working with Messages
3. Topics & the Focus Pane
4. Composing & Sending
5. Responses & Placeholders
6. Signatures
7. Searching

Composing & Sending

One of the things Postbox does really well is to help you send better emails. Postbox is packed with features for writing, formatting, and sending emails within its thoughtfully considered and well-laid out Compose window.

First is the toolbar. You can customize the toolbar to your liking, but out of the box it has buttons for sending messages, inserting responses, including attachments, adding a signature, or saving messages to a specific folder. There’s also a handy sidebar that can help you find contacts, attachments, or images.

Underneath the toolbar is the From Bar, where you can select which account you wish to send from. Below the From Bar are the addressing fields. To show or hide fields such as CC or BCC, right-click and select your options from the contextual menu.

Domain Fencing

One very cool feature that's unique to Postbox is Domain Fencing, which prevents you from accidentally sending an email to the wrong person or from the wrong account. To set this up, go to Preferences or Options and then select Accounts > [your account] > Composition. From here, you can set up one of two options in the Addressing section based on specific use cases.

If you work in a company or organization, you may want to make sure you don’t unintentionally send any messages to the outside world from your work account. In this case, check the "Mark addresses not ending with:" checkbox, and enter the domain name for the company or organization domain to stay within. You can add fences for multiple domains by entering their names in the field, separated by commas.

It can be easy to send a message from the wrong account when you’re moving fast, for example, sending a work email from your personal account. In this case, enable "Mark addresses when sending to:" and enter any domain names you don’t want to mistakenly send messages to, again, by adding domains separated by commas.

In both of these cases, whenever you attempt to address a message to any of the fenced domains, the address will turn RED in the Compose window to warn you. Of course, you’re always free to send the message anyway if you want, but Postbox will alert you so you don’t do it accidentally.

Composing Your Message

Next is the Formatting Toolbar, which allows you to format the text in your message body. The Formatting Toolbar contains common options for font family, size, style, and formatting. By clicking the Code View button, you'll have access to a full HTML editor, providing you with fine-grained control over the design and content of your email.

Next is the message body, where you can compose your actual message.

When composing a message, you can press and hold any key to bring up a set of International Characters. To insert a character, type one of the number keys 1-9. If more than 9 options are available, click the + or type the + sign to display additional options. Some character keys are supported as well (for example, try holding down the quote key). There may be cases where disabling the International Character Input mechanism is desired. To turn it off, navigate to Preferences on the Mac or Options on Windows and select Composition > Typing, then disable the checkbox for International Characters panel.

You can also add emojis to your messages, and Postbox makes this super easy. Simply type the colon key followed by the name of the Emoji you wish to use. As you start typing, you can auto-complete or use the arrow keys to navigate to your desired Emoji. If needed, the Emoji input panel can be enabled/disabled in Preferences > Composition > Typing.


Next, let's talk about images because Postbox provides a whole suite of tools that let you do almost anything with an image.

When you add an image to the message body, the Message Size Indicator will inform you of the total message size, including all text and images. This is important because some ISPs have size limits for messages sent through their servers. For example, Gmail places a 25MB limit on email messages. So you can set Postbox to warn you if you go above a certain threshold in Preferences or Options > Composition > Typing.

When image width or height exceeds 320, 640, or 1280 pixels, resize icons will appear that will allow you to size the image to those maximum dimensions. Select the image you want to resize, then click on a resize icon to scale the image down. Deselect the resize icon to revert the image to its original size and resolution.

You can also apply effects to images by right-clicking an image in the message body, selecting Modify Image or Modify Selected Images from the pop-up menu, then selecting an effect. To disable an effect, select it again to toggle it off. Some of the effects include:

  • Scaling, which gives you Large, Medium, Small, and percentage scaling.
  • Float, which aligns the image to the left or the right, and allows your text to wrap around the image.
  • Margin, which allows you to add a 10px, 20px, 30px, or 40px of margin on all four sides of an image. Of course, you can always jump into HTML edit mode to fine-tune these settings.
  • Flip, which flips the image horizontally or vertically.
  • Rotate, which rotates the image clockwise 90, 180, or 270 degrees.
  • Effects, including Greyscale, Retro, Sepia, Solarize, or Vintage.
  • Frames, which gives you 11 different frame effects for you to enjoy.
  • Shadow, which adds a soft shadow around the image.

Composition Goals

Below the message body, you will see your Composition Goals if you have them turned on. Composition Goals can let you know when you’ve hit the desired character limit, word limit, or amount of time you want to spend on composing an email. These are soft limits, so once you’ve reached your goal you can choose to wrap things up or keep going.

To turn on composition goals, go to the Postbox menu on Mac or the Tools menu on Windows and select Preferences or Options respectively, then Options > Composition > Advanced. Next, select the Set composition goals checkbox. Finally, select a combination of Character Count, Word Count, and Stopwatch and set the values for the chosen options.

These goals will now display below the Message Body in the Compose window. When you reach a goal, its counter in the Goals Status bar turns red to let you know. Note that if you switch away from the Compose window, Postbox knows to pause the timer until you return. You can show or hide the Goals Status bar by checking or unchecking Goal Status in the View menu, or by clicking the Goals button in the Compose window toolbar.


Below the Composition Goals Bar, you’ll see the Attachments Pane. Attachments are represented as icons that can be manipulated as if they were in the macOS Finder or Windows Explorer. An attachment can be saved via drag & drop, or to save all attachments to a specified destination, you can use the Save function at the top of the panel.


The Compose Sidebar offers another set of powerful capabilities. It displays recently or frequently accessed attachments and images from your email store. Postbox displays your ten most recent or frequent attachments and images by default, and you can click the "Load more results button" at the bottom of the sidebar to see more results. Or, if you prefer, you can search for an attachment or image using the Search field at the top of the sidebar. To use an attachment or image, simply double-click or drag and drop the file from the sidebar into the message. This is particularly handy if you reuse the same attachments or images often, for example, a resume or profile photo.

Finally, one of the most powerful features in the compose window is the Quick Bar, which lets you quickly add a signature, a canned response, or a topic. To activate the Quick Bar, type Command-L on Mac or ctrl-L on Windows. Once the Quick Bar appears, start typing the name of the signature, response, or topic you desire. Autocomplete against the top result, or make a selection using your mouse or up and down keys on your keyboard. Press the enter key to add your selection to the message.