Formal:
* Avec amour de Maman: This is the most formal and literal translation.
* Avec tout mon amour, Maman: This emphasizes the depth of your love.
Informal:
* Avec amour, Maman: This is a more casual way to say it.
* Gros bisous de Maman: This means "Big kisses from Mommy" and is a very affectionate way to sign off.
* Je t'aime fort, Maman: This means "I love you a lot, Mommy" and is a very sweet and personal way to sign off.
The best option for you will depend on the context and your relationship with the recipient.