how to change mail:pass to username:pass

Apologies if this question has been answered already I've been searching everywhere but cant find a solution I basically want to

change for example e - mail | password

to this > deanimperato1|london44

so basically cutting out the domain and leaving the id
I have 5m list I want change at least 100k however I refuse to do it one by one I'm sure there is a way as checkers like ione do this for you automatically.


P.S I'm a bit of a noob so please spare me the advanced terminology

Use edit plus or similar text editor.

Use Find & Replace option and remove the domain.com from the list.

Thats it

Open the file with Excel and it will prompt you to specify the delimiter, just enter "|" as the delimiter character and finally swap the columns and save it back.

I use Notepad++ for things like this. Use the find and replace tool. (CTRL + F)

Alright I'll go ahead and use Notepad++ as I already tried excel