we have evidence of widespread irregularities in casting votes via mail for people abroad in italian elections (there are a ton of italian citizens abroad, due to ius sanguinis rules).

That entails basically going to people, buying a voting slip and casting it on their behalf. Or better, buying packs of slips from officials. For e-voting it would be the same.

Sure, you can increase jail time and reward revealing it, but that is not a panacea, as the existence of _any criminal activity_ proves.