Answered Best way to compare email address to whitelist on registering

I want to compare a users email address to a long list (about 1000) email addresses and only allow registration if the email address exists in the list. What would be a good and easy to maintain way to do this?

1) create a text file with the list, each address on a new line, and create a preHook for the Register snippet to read the text file line by line until the address is found, and return true or false - would this be too slow because of the 1000 lines in the text file?
2) create a chunk that contains all the email addresses and check that contents with a preHook - would this be faster than the first option? Would it be too big for a chunk?
3) is there a better way?

It would be most useful if all addresses can be pasted, one address per line in a chunk or file, this is easiest for my client.

OR a different approach: somehow automate the creation of users for all the 1000 email addresses and email a password to each of them. Is there a snippet for that?

Any thoughts and ideas would be appreciated!

I'm glad it works.

Nice job of putting the logic for failed searches into the snippet.

On further thought, this might be a little faster, since you're only testing a single value. Using array_flip is faster if you're going to be looking for multiple values. The time difference would probably be negligible unless you have a very long whitelist.

Thanks! What would be 'very long'? (this one could potentially have a 1000 email addresses in it.. is that very long?)

Good question, I don't really know. I'd say if things slow down enough to notice when the list gets longer, try it the other way and see if it speeds things up.