Each Maryland corporation shall have: A principal office in this State; and A resident agent. A corporation may designate or change its resident agent or principal office by filing for record with the Department a certified copy of a resolution of its board of directors which authorizes the designation or change. A corporation may change the address of its resident agent by filing for record with the Department a statement of the change signed by its president or one of its vice-presidents. A designation or change of a corporation’s principal office or its resident agent or his address under this subsection is effective when the Department accepts the resolution or statement for record. A resident agent who changes his address in the State may notify the Department of the change by filing for record with the Department a statement of the change signed by him or on his behalf. The statement shall include: The names of the corporations for which the change is effective; His old and new addresses; and The date on which the change is effective. If the old and new addresses of the resident agent are the same as the old and new addresses of the principal office of the corporation, the statement may include a change of address for the principal office if: The resident agent notifies the corporation in writing that the statement will be filed; and The statement recites that he has done so. The change of address of the resident agent or principal office is effective when the Department accepts the statement for record. A resident agent may resign by filing with the Department a counterpart or photocopy of his signed resignation. Unless a later time is specified in the resignation, it is effective: At the time it is filed with the Department, if the corporation has appointed a successor resident agent; or Ten days after it is filed with the Department, if the corporation has not appointed a successor resident agent.