I received an email from a friend stating that the gatekeeper of the Ka'bah had a dream and I have to distribute five copies otherwise something very bad thing will happen to me or my family. Is it true or false? I want a detailed answer to send to my friend in US and he believes in these things.

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

The so-called testament you mentioned is definitely a lie and there is no origin for it. Moreover, dreams can not be considered as a source of religion and nothing can be established through dreams. Every Muslim who receives the mentioned testament should destroy it, warn people against such claims and put his trust in Almighty Allah. Actually, many religious people knowing that Allah has predestined everything, ignored it and did not face any ill effects. So, when something happens to someone after having destroyed such lies this would have happened to him as it is predestined. But Satan will try to make him believe that it is because of his destroying such trash. This reasoning is only temptation of Satan. One should turn away from the temptations of Satan and believe in Allah, that what happens for him is due to the will of Allah.
One should know that everyone who participates in writing or distributing such myths commits a grave sin and cooperates with wrong-doers in spreading evil. Allah Says (interpretation of meaning): {Help you one another in Al­Birr and At­Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression.} [5:2].
Here is Shaikh Bin Baz's Fatwa concerning the mentioned testament. One person asked him about the testament of a person called Ahmad, the keeper of the keys of the K'abah. He told the Shaikh that he found in that testament many statements contrary to the true faith. He spoke with some brothers and tried to convince them that it was only a lie. But they did not pay any attention to him and widely distributed the statement. So, he asked the Sheikh to give a Fatwa about it. The Shaikh (May Allah have Mercy on him) replied: "This bulletin and what is mentioned in it, i.e. the benefits for the one who gives it special importance and disadvantages for the one who neglects it, are nothing but lies and myths. Distributing it is forbidden. Whoever does so will commit sin and deserves punishment sooner or later, as the consequences of innovations are very bad. The above mentioned bulletin is an innovation and a lie against Allah. Allah Says (interpretation of meaning): {It is only those who believe not in the Ayât (proofs, evidences, verses, lessons, signs, revelations, etc.) of Allâh, who fabricate falsehood, and it is they who are liars.}[16: 105]. The Prophet said: "If anyone tries to introduce in to this faith of ours (Islam) something, which is not a part of it, it is to be rejected (and that person is condemned).
In another Hadith the Prophet said: "If someone practices that which is not authenticated by me, it is to be rejected". Every Muslim is obliged to destroy such things and warn people against such myths. We and other people neglected it, yet we did not face any bad affects, only all kinds of blessings. Therefore, everyone who participates in writing the above testament, distributing it, inviting people to it or propagating it, is a wrong-doer since all the mentioned activities are a cooperation in sin and transgression, and in propagating Bidah (innovation).
We ask Allah's protection for us and for all Muslims. We pray Allah to deal with the fabricator of that testament, as he deserves, since he has spread lies and made the people busy with those things which only harm them and bring them no benefits.
Allah knows best.