A technical release under seal, given to one joint promisor, will inure to the benefit of all,1 unless the promisee expressly reserves his right to proceed against the remaining promisors." This rule applies to the technical release under seal only.3 An oral release does not have this effect;4 nor does a release for a Valuable consideration discharge even the promisor to whom it is given, unless by statute.5 A covenant not to sue made with one joint promisor does not discharge the others.6