Complex sentence: The expression of feelings may be made to an existing love or in the hope of establishing a new relationship; and the increasing rarity and consequent emotional charm of personal mail may also serve to emphasize the emotional importance of the message.
Split into simpler sentences: The expression of feelings may be made to an existing love or in the hope of establishing a new relationship. The increasing rarity and consequent emotional charm of personal mail may also serve to emphasize the emotional importance of the message.