You have good reason to feel uncomfortable when you receive this kind of email. While there is certainly nothing wrong with asking your email contacts for prayer, when the request attaches conditions such as, “You must forward this to 10 people or you’ll break the chain and no prayers will be answered” it becomes nothing more than a superstition.
The same is true for those “Novena Never Known to Fail” prayers of which nine copies are left in nine different churches in order to receive the requested favor.
By attaching these conditions, we are no longer hoping for favors from the goodness of God as much as we are counting on the “magic effect of this unbroken series of prayers,” the Catholic Dictionary explains.
“The efficacy of the practice, therefore, is mainly in the chain and not in the prayer. All forms of chain prayer are superstition and correspondingly sinful.”
We are warned in the Catechism that to "attribute the efficacy of prayers or of sacramental signs to their mere external performance, apart from the interior dispositions that they demand, is to fall into superstition" (CCC 2111).
Superstition is a violation of the First Commandment, which is how chain prayers, whether by email or any other means, can become an occasion of sin.
"Superstition is the deviation of religious feeling and of the practices this feeling imposes. It can even affect the worship we offer the true God, e.g., when one attributes an importance in some way magical to certain practices otherwise lawful or necessary" (CCC 2111).
God does ask us to bring our needs to Him in prayer, and it is an act of charity to lift up the needs of others, but we need to exercise our faith by confidently leaving these requests in His hands. If we want to attach anything to these requests, Scripture suggests adding a sacrifice or a fast. This is what David did the night his child became sick and he spent the night lying on the ground, fasting and praying (2 Sam 12:16).
However, the end result must always be left up to God, and never to our own resources.
The Learn to Discern Compendium has a full chapter dedicated to explaining superstition and how it can weave its way into our devotions. Click here for more information!