our mayor, the honorable, Richardo Emanuel
On the envelope you would put 'Mayor John Doe.'
Only informally face to face . If he is not currently holding office, the title is not his anymore.
Depending on your familiarity, "Mr. Mayor," "Mayor Smith," or Joe.
Not it is not, with an other than honorable discharge you have been you can be dicharged (kicked out) for many reasons. These reasons being you conduct, not meeting weight standrads, testing positive...