For normal business correspondence the phrase "the Honorable" is usually omitted. "Consul John Doe" or "Consul General Jane Doe" are quite sufficient (and quite important in the case of non-career consuls who, unlike career officials, have legally separate private identities). Consul General Jane Doe or Consulate General of Roxania Address
Ms/Miss/Mrs Jane Doe Consul General of Roxania (Often seen in the U.S.)
If more formal usage is required for social or official occasions, the accepted form is: The Honorable John Doe Consul of Roxania Address
or
The Honorable John Doe Consul for Roxania (Sometimes used to indicate Heads of Post)
Following time-honored European custom, the word used in the Vienna Convention to designate non-career consular officers is "honorary". The word has antique but precise legal meaning under the Convention, but is not part of a consul's title under the VCCR. Nor does it correspond to the popular usage of the word, "in name only" or "without power or authority", as both career and non-career officers are accorded equal powers under the Vienna Convention. An equivalent to this is the military where no distinction is made between the titles of regular and reserve officers. (A US Army Reserve colonel's title is "Colonel".)