Don't use a sledgehammer to crack a nut
Literally 'don't kill flies with cannon shots'. Advises against using disproportionately large or complex solutions for small problems.
An email was enough. Don't use a sledgehammer to crack a nut.
—You're calling a meeting for that? —Don't use a sledgehammer to crack a nut.
The response was over the top. Don't use a sledgehammer to crack a nut.