Good afternoon community, 

So on a Visualforce Email template I'm trying to add a link back to the record detail page, with:

<apex:outputLink value="{!URLFOR($Action.Lead.View, relatedTo.id)}">
</apex:outputLink>

where related to type is my standard Lead object.  on Saving this template i continue to get this error:

Error occurred trying to load the template for preview: Invalid parameter for function URLFOR. Please try editing your markup to correct the problem

I'm not a developer by trade so not sure how to correct this, would appreciate any feedback regarding how to fix ....

thanks everyone