How to filter out popular email domains with regular expressions?

Hey everyone! I’m working on a project where I need to sort through a big list of email addresses. The tricky part is I want to remove all the common ones like Gmail, Yahoo, and Hotmail.

I’ve got a regex that works for Gmail: ^[a-z0-9](\.?[a-z0-9]){5,}@gmail\.com$

But I’m scratching my head on how to make it work for Yahoo and Hotmail too. Any regex wizards out there who can help me expand this to cover all three? I’m not super experienced with regex, so a simple explanation would be awesome.

Also, if there’s a better way to approach this whole thing, I’m all ears! Thanks in advance for any help you can give!

I’ve tackled a similar challenge before, and I found that using a regex with alternation works well for filtering multiple domains. Here’s a pattern that should cover Gmail, Yahoo, and Hotmail:

^[a-z0-9](\.?[a-z0-9]){5,}@(gmail|yahoo|hotmail)\.com$

The (gmail|yahoo|hotmail) part is key – it matches any of those three domains. You can easily add more by including additional options in the parentheses, separated by |.

One caveat: This approach assumes the domain part is exactly as written. It won’t catch variations like yahoo.co.uk or outlook.com (which is now more common than hotmail.com).

For a more robust solution, you might want to consider maintaining a list of domains to filter and using a combination of string manipulation and regex. This would give you more flexibility to update the list as needed without modifying the regex itself.

While regex can work for this task, I’d suggest a different approach that might be more maintainable in the long run. Instead of using a complex regex pattern, consider creating a list or set of popular domains you want to filter out. You can then simply check if the domain part of each email address is in this list.

Here’s a basic Python example:

popular_domains = {‘gmail.com’, ‘yahoo.com’, ‘hotmail.com’}

def filter_email(email):
domain = email.split(‘@’)[-1].lower()
return domain not in popular_domains

This method is easier to update and understand, especially if you need to add or remove domains frequently. It’s also more efficient for large lists of emails, as it avoids the overhead of complex regex matching.

hey there! i’ve dealt with this before. instead of regex, why not use a simple python function? something like:

def is_popular_domain(email):
popular = [‘gmail.com’, ‘yahoo.com’, ‘hotmail.com’]
return email.split(‘@’)[1].lower() in popular

it’s way easier to maintain and update. plus, it’s faster for big lists. just my two cents!