Skype Users: If you see phone numbers that look like this or this iinstead of like this you need to temporarily disable Skype's click-to-call functionality during the entire installation process, from start to finish. The easiest way to disable this is to remove or uninstall the "Click to Call with Skype plugin" via Windows' Control Panel's Add/Remove or Uninstall Program function. Skype click-to-call can also be deactivated by disabling the plugin through your browsers' manage add-ons/plugins options (actual procedure varies according the browser type).

FAQ's (These may be helpful AFTER installation): https://dynasend.com/pages/email-signature-user-faqs.html

POSTBOX EMAIL SIGNATURE INSTALLATION INSTRUCTIONS

Note: Installing an email signature in Postbox requires pasting the HTML (computer) code itself - we will not be copying and pasting the signature itself. The first three steps of these instructions explain how to copy this compute code to your computer's clipboard.

PART 1 - COPYING THE EMAIL SIGNATURE HTML CODE TO YOUR COMPUTER'S CLIPBOARD

To If you don't currently have your signature open in a browser tab, display it now: enter your email address and then click the "Click to Display" button

  

Now go to the tab that is displaying your signature and RIGHT click on the window's white space beneath the signature and select "View Page Source" (see below).
Postbox email signature installation - image sub1
You should then see the actual computer code that makes up your signature (see below).
Postbox email signature installation - image sub2
First, press either Command-A (Mac) or Ctrl-A (PC) to select all of the computer code. It should all be highlighted in blue (see below).

Second, press either Command-C (Mac) or Ctrl-C (PC) to copy the code to your computer's clipboard. You will not see anything happen as you do this.
Postbox email signature installation - image 9
PART 2 - PASTING HTML CODE INTO POSTBOX

Go to your Postbox Inbox and click TOOLS in the top menu and pull-down to OPTIONS (see below).
Postbox email signature installation - image 1
Click IDENTITY and then click the top EDIT button (see below).

Note: If you have multiple email accounts set up, make sure that you are working with the email account that you want to apply the signature to.
Postbox email signature installation - image 2
Now type a name for your signature.

Then click the little "paper" icon located at the right end of the formatting toolbar - if you hover over this icon you'll see "HTML" (see below).
Postbox email signature installation - image 3
You should see a pop-up dialog box that is labeled "Insert HTML" - place your cursor inside this box and press either Command-V (Mac) or Ctrl-V (PC) to PASTE your email signature's HTML computer code (see below).
Postbox email signature installation - image 4
With the code pasted into this dialog box, click INSERT (see below).
Postbox email signature installation - image 5
You should now see your signature (possibly enclosed by some ugly gridlines) in the signature dialog window. Click OK (see below).
Postbox email signature installation - image 6
When you go to compose a message you should new see your signature. Please note, the gridlines will be visible while you compose your messages. The gridlines will not appear to the recipient when they have received and are reading your message. They may appear temporarily when the recipient clicks reply and is writing back to you. All email has two modes - "compose mode" and "read mode" and they behave quite differently from one another at times (see below).
Postbox email signature installation - image 7
One final note: Any clickable hyperlinks in your email signature will not work while in "compose mode" but should work properly when your message has been received and is being read.