Issue with URL and characters

Hello,
I have an issue with the use of an other plugin (User Submitted Posts = USP) which is sending an email with a post URL in the body, when someone is submitting a post.

When Mailpoet is the sending service for all my wordpress email and when the mail send by USP through mailpoet are HTML i have a “character issue” the “=11” in the URL are substituting by a strange character and the link become wrong.

When i disable sending by mailpoet (set to be send by my own wordpress) and use HTML the link is good..

Have you any idea how to fix it ? Thank you very much !