Picking Domain from Contact Email

Picking Domain from Contact Email

Hi,
I would like to ask how it can be done to automatically to read from Email (e.g. 123@abc.com) the domain (in this case "abc.com") and place in a new field. I believe a new custom field using a formula (prop. using Substring is the best, but I have not a fix number when it should start/end reading as you could have 123@abcdefg.org or different). Can you help please?
Thanks
Ben