How to extract only the top level domain (TLD) from email addresses?

[ICAJschuster]

I am working with an email application. Currently doing a report based on domains using the product. Issue is there are many, and often arbitrary sub-domains. This is what I'm currently using:

rex field=Sender ".[^@]+?@(?<sender_domain>.+)"

The results from that look like:
test.com
sub.test.com
why.so.many.subs.echo.com
a.echo.com

So what is the "right" way to get the last 2 fields on either side of the last DOT in the field?
This is close but it only matches IF there is a subdomain and many are just TLD:

   rex field=Sender ".[^@]+?@.*(?<sender_domain>\.\w+\.[a-zA-Z]+$)"

Thanks!

[cpetterborg · Accepted solution]

Try:

rex field=Sender "(?P<sender_domain>[A-Za-z0-9]+\.[a-zA-Z]+)$"

All you need is to look at the last part, not the whole email to get what you need, and this will find it easily.

[acharlieh]

This is indeed what was asked for, however, depending on what you're doing with this, you may want to look a bit deeper:

1) "Top Level domains" for some country codes you may actually want the 3rd level. For example: "amazon.co.uk"
2) You need to include hyphens and other characters as well, otherwise you may miss some domains. Of note internationalized domain names are actually prefixed: xn--

[ICAJschuster]

Perfect! Thank you so much!