Mutual reception is said to be "beneficial;" the two planets cooperate and mutually support each other. Reception means "to be in touch with each other." The two planets are "informed"** of and by each other, mutually sustaining. The word may imply taking on some burden.
My experience suggests that if the planets are naturally inimical, in hard aspect, or otherwise badly conditioned, mutual reception can exacerbate harm. I would interpret mutual receptions with prudence.
In the chart above, Moon is lord of the Sun and she is posited in the 12th House. She rules the three 10th House planets, which "stand above all else" [they are very powerful and dominant forces in the life], from this disadvantageous position. If you use the traditional rulerships rather than the modern ones, Moon disposes every planet in this chart except for the independent Venus. Rulerships are very powerful factors in horoscope interpretation; when a planet rules all the others or many of them, its influence in the life is greatly enhanced, for good or for evil. Look up, in your dictionary, the words "rule", "lord", "prince", "king", "determine," and "dispose"...these words describe the function of the lord of a sign (house cusp and affairs of the house) and of the planets in the sign.
Mercury is not only lord of the Ascendant, but rules the Midheaven (10th cusp) as well, and the house he occupies; he accrues power through these rulerships of powerful angles. The Angles of the horoscope are the most powerful and dynamic points in a chart; the planets ruling them therefore acquire additional power over and above what they hold for other reasons.
I would find it very difficult to ignore a mutual reception between two such powerful planets. And by the way, Mercury and Moon are in aspect: There is an exact semisquare between them.
How to intepret this relationship of Moon and Mercury? Suggestion: first, read everything you can find on "Moon" -- her sign position, house position, the aspects she beholds, her position as lord of 10th and 11th (she is not technically lord of 10th, but rules the three planets there and receives one of them) in the 12th, and so on. Do the same for Mercury. Write it all down, a separate page for each of the two planets (or if you feel ambitious, the ten planets).
Once you have done this, you now have statements about yourself instead of meaningless (in real-life terms) astrological jargon. Compare the two statements about yourself and see how they might assist or hinder you. This chart is about you and your life, not about "Moon in the 12th House" -- what does that mean to you? What does that position imply for you as a human being, in terms of living? Think in those terms rather than in terms of astrology. The astrological terms tell you about the condition of the different planets (different psychological aspects of yourself, people in your life, etc) and of their condition, how they function in your life, and how they relate to other factors. They describe the power of each planet. This allows you to weigh the horoscope. But unless you translate these astrological terms into meaningful statements about yourself you might as well go watch The Simpsons. You must use "the astrology" to go beyond the astrology and probe the depths of the life.
The Moon is very powerful in your chart. She is the mother, who is the source of whatever else the Moon implies. She is where it started. Moon in your chart is Common and Earthy. She is dependent (12th House), needs help and support. She is in a dark place and out of touch, confined, sad.... Note that Sun supports Moon by sextile, and she has power over him by rulership; he will do as she asks, support her needs.
** to give evident substance, character, or distinction to; pervade or permeate with manifest effect: A love of nature informed his writing.
4. to animate or inspire.
5. Obsolete (n.b., these words come from times past; their "obsolete" meanings are important.]
a. to train or instruct.
b. to make known; disclose.
c. to give or impart form to.