When there is an active chat between your Mac and another device, use the box near the bottom of the chat window to send messages.
You can click inside the box to start typing there, or the main menu command "New Message…" will also put the keyboard insertion point inside the box.
You can send text, files, and images. Underpass accepts any Unicode text characters, including emoji. Text can be typed in the box, pasted, or dragged from another application. There is a convenient button at the bottom of the chat window to open the built-in macOS Emoji & Symbols panel.
In addition to text, Underpass allows you to send almost any kind of file. The file transfer will be completely encrypted, just like all text is encrypted. You can drag a file from Finder and drop it in the box, or copy the file in Finder and paste it in the box. With image files, both the sender and receiver will be able to see the image itself in Underpass, as long as the device has built-in support for the image format. Popular image formats such as JPEG, PNG, TIFF, and even animated GIF are displayed.
You can also paste or drop an image that doesn't come from a file. For example, you can take a screen shot that is copied to the clipboard, and paste the screen shot directly into Underpass without having to save it to a file. These images will be fully encrypted too, of course.
Underpass does not currently support sending file folders or packages, such as
app bundles. Underpass will send
zip files, however, so in order to send a folder, you should first compress the folder into a
zip file and send that.
When you have entered your message in the box and want to send it, just press the return key. The return key sends the message and clears the box, readying it for your next message. You and your chat partner can type and send messages simultaneously. While you are entering a message, but before you send the message, your partner will see a status line at the bottom of the window to know that you are typing.
You can send a file of up to 4 GB in size with Underpass. When you send large files, it is important to note that Underpass sends each message sequentially in full. After you send a file, you can immediately start typing again and send another message, but the other device will not see the second message until the entire file has been received, which may take some time, depending on the speed of your network connection. The receiver will display a status line at the bottom of the window when a file download is in progress.
Next: Save received files