Legal Question in Credit and Debt Law in Maryland

There are at least two bodies of law that may apply--- First, contract law will dictate how notices need to be given between parties. Thus people are generally free to agree (in a service contract for instance) that to be effective, communication must be in writing, sent by certified mail, etc. Secondly, there are laws relating to digital signatures (when an email can be a "signed writing") which boiled down to their essence basically say both parties must agree to treat online consents, etc. as signed writings for them to be as effective as a written signature on a piece of paper.

Practically, going into a branch might be your quickest source of information. Otherwise, one would send the request in the format specified by the bank / lending institution and/or the paperwork signed when the account was opened.