City Council Councilman Ruben Diaz Sr. may have technically violated council ethics rules, but it’s hard to see any harm in his use of his official email to send out mildly catty commentary.

After all, the Bronx Democrat sent the same “What You Should Know” letter for years from his state Senate account. And its content is no more self-serving or political than what other city officials send out — just more provocative.

Indeed, the missive that apparently spurred the July 16 complaint was one where Diaz asked why some gay groups were going after Gov. Andrew Cuomo, who helped legalize gay marriage in New York, rather than Diaz himself — who long fought to prevent it.

As for the Ethics Committee finding this is “misuse” of government resources: No one’s going to think his writings, with their highly distinctive “voice,” represent official council positions, or anything but his own opinions.

And email is free: He’s not wasting taxpayer cash. Some readers may think he’s wasted their time — but Diaz’s notes are the only regular missives from any New York official that anyone reads for fun. (Is jealousy is behind the whole kerfuffle?)

Anyway, the solution’s obvious: Diaz can just start sending from a campaign or other non-city account, and leave his critics to steam in silence.