When editing the text on Step 7: Email Options of Personal Fundraiser you can create line between paragraphs in the email template by hitting Enter twice. Those blank lines are being removed when the email is sent through a participant's Personal Fundraiser site.
If you would like there to be a blank line between your paragraphs, you can put a space in the blank line so it will not be removed.
Steps to Duplicate
Click on the name of your fundraiser
Click on Step 7: Email Options
Place the cursor in the Email Template text box
Enter in some text, click Enter twice, and then enter more text
Click Preview This Template; you will see that the blank line between the paragraphs has been removed