Individual letters usually stand for something, such as a person: for example, the letter “g” or the sound of a “g” may stand for “george,” or some other signiﬁcant person or object in a person’s life. ... New American Dream Dictionary
If you dream of receiving a letter that is delivered by hand, it is an indication that you have done something which is not considered upright by your lover, A letter written with white ink on a dark paper is an unlucky portent. It indicates separation between husband and wife or between lovers, and it may be accompanied by unwholesome allegations.
A warning that you should beware of unworthy concerns is contained in a dream of trying to hide a letter from your sweetheart, wife, or husband.
A registered letter is a portent of family troubles and selfishness on the part of one or the other of two lovers. Jealousy of a rival is indicated by a registered letter.
A happy letter of an affectionate nature is a pleasant augury; but if it is written on colored paper, it indicates that there will be difficulties in love or in business. Written in blue ink on white paper is a sign that you will be lucky in love and in money matters.
A maiden who dreams of receiving a letter from her lover and placing it close to her heart will have cause to be worried by a beautiful rival.... The Complete Dream Book
To dream that you receive a Letter, is a sign of unexpected news; but if you post or send a Letter, then you will meet some unexpected difficulty that will upset your plans, but may not cause any real loss. Letters are a sign of something unexpected.... Mystic Dream Book