Holiday,
Email Covers attempt to use the width of the memo from when the cover sheet was entered.
Bruce is correct that when entering the coversheet you can re-size the form and when the cover is generated it will create the lines at that width.

I would put the URL's at the start of a line if you want to make sure they are not broken up.

Email covers in Adagio are treated as plain text, so there is nothing that will keep a long URL together. It's the receiving email program that looks at the text and makes it into a clickable URL.