But spellcheckers don't work with emails because it's up to the user what they put in as an email address?

madeupnonsense.a.b.c.d.e.blergahlot@...per.mail.co.uk could be a valid email address which fails a spellcheck. Should that just be rejected outright because it failed a spellcheck? Because it has more periods in it than expected?

This program is designed to just send an email to whatever email address the user inputs. It is up to the user to make sure that is correct, not the program.