Validation phase of normalizeEmail lacks flexibility

[noinkling]

normalizeEmail currently starts by calling isEmail. This might make sense as a guard, but there is currently no way to pass in options, which may result in false negatives for people who make use of the options, particularly require_tld. Additionally it's simply not obvious that normalizeEmail also validates unless you look at the code; this might be resulting in people doing unnecessary double validations.

I can see a few ways to solve this:

• Allow passing in additional options for the isEmail call, and clearly document that this is a "2-in-1" function.

• Pass in the most permissive set of options, i.e. { allow_display_name: true, require_display_name: false, allow_utf8_local_part: true, require_tld: false }, and let the user handle any more restrictive validation beforehand.

• Remove the isEmail call altogether and let the user handle any validation beforehand. Or provide an option to do so. This is my preference because I think that normalizeEmail should only be responsible for one thing.

Display name support might need to be added if it's desired.

Actually I ran across this because I'm primarily using Joi for validation in a Node app (just because it is schema-based and has structured errors built-in), but I'm also using this library for the email normalization (among other things). I found email addresses like "whatever@local" that passed with Joi's defaults (refer to this) weren't passing normalizeEmail's check. isEmail has the require_tld: false option that would fix this, but there's no way to pass it through. As a workaround, Joi has a similar option minDomainAtoms which can be set to 2 to better match this library's default behavior, but it's still a workaround... as a general principle I'd rather just not have (restrictive) validation unless I ask for it.

[linkinmedo]

I agree with you that option 3 is the logical one, if @chriso agrees I'll work on it.

[chriso]

Yeah agreed, we should remove validation and add a caveat to the README that says that the result is undefined unless the input is an email.