The following types of additional offices may be established and maintained by a savings bank:(1) branch offices at which the savings bank may transact any business that could be done in the home office;(2) mobile facilities at which the savings bank may transact any business of the institution which could be done in the home office (a detailed record of the transactions at such facility must be maintained); and(3) courier/messenger service to transport items relevant to the bank's transactions with its customers, including courier services between financial institutions.