Landlords don't usually tell tenants that their offer of an annual rent of $490,000 is "disappointing and needlessly provocative".

But that's what Michael Donovan did, in a letter last June to the tenant of his South Melbourne property, electricity giant CitiPower.

CitiPower runs a power substation on the chunk of land owned by Mr Donovan, a director with commercial real estate agents Fitzroys.

And - thanks to a rezoning of the land in 2012 - when Mr Donovan told the power company to go jump, they were forced to ask "How high?"