We send a link to the courier's track-and-trace webpage for boxes we ship and this quick hack was the easiest way I could see to do so in DEAR.
Set up the URL to the track-and-trace as the "carrier" in Settings. We use two different couriers, plus the option to pick up.
Add these MailMerge fields to your email template:
The result comes out like the attached screenshot. It's worth noting that some email clients like Gmail will only format the <<carrier>> as a clickable link...I've tried adding various bits of html and the Excel <hyperlink> tags to no avail so if anyone knows a workaround please let me know!
Hope this helps somone.