First of all: The mail that you want to do this in needs to be saved at least once.
Then you can follow these steps to create clickable links:
Using the Notes Client
Create the Anchor:
Open the document you want to link to in Edit mode. Place your cursor at the beginning of the paragraph you want to jump to.
Copy the Link:
Go to Edit > Copy as Link and select Anchor Link. A small anchor icon will appear next to the paragraph.
Paste the Link:
Go to the document where you want to place the link. Click where you want the link to appear and choose Edit > Paste. The anchor link will now be a clickable link.
If you want to make a “clickable” Text instead of the link icon, just mark some text that should link to your anchor, then click on Create > Hotspot > Link hotspotand as long as your “Anchor” is still in the clipboard it will automatically populate the dialog for you