A valve for adjusting the flow of water through an oral irrigation device connected to a shower head is located on a handle connected to a water-dispensing syringe or pick. Due to an elastically deformable bladder disposed inside the reservoir, a gas chamber in which gas is sealed is formed between the bladder and the outer casing, and a reservoir chamber communicated with the inside of the cylinder and designed for guiding hydraulic fluid is formed between the bladder and the cylinder. For each sub-mailbox, the voice mail account will define a respective pass code that can be used as a key for gaining management access to that sub-mailbox and to the general mailbox but not to any other one of the sub-mailboxes.