I'm testing the version 4.0.3. Downloaded 1 hour ago. Are the new triggers already implemented? I don't find them in the trigger list but I type in the trigger you suggest me and I change email address, the auto action is executed.

Yes they're implemented, but no they won't show in the dropdown list.

Anyway the autoaction is executed without conditions assigned meanwhile I need this: if the new email address contains a specific domain for the email address (@mydomain.example) then the auto action must be fired otherwise not.

If you're using the after confirm trigger then the email address will already be updated to the new address so all you need to do is just condition for the email domain.

contains @maidoman.example [var1_email] contains @maidoman.example [var3_email] contains @maidoman.example but no way. If those conditions are applyed the auto action is not fired, if I remove those conditions the auto action works. What's wrong?

There is no var3 compare usage. If you need the old and the new email address for comparisons then see my previous reply where I've provided what variables the trigger has. var2 is the reconfirm email object which contains both the new and the old email addresses. Your usage however should work by just removing your var3 condition. I would use either of the below conditions.

OR
If the contains operator isn't working for this then you'll probably need to use regexp as follows.

OR