Peace and mercy of Allah be upon you.
The signatures found in our sources and collections are numerous, with some being transmitted by Sheikh Al-Kulayni, Sheikh Al-Saduq, Sheikh Al-Tusi, and Sheikh Al-Mufid, may Allah have mercy on all of them. Their books are among the most important sources that transmitted his (AJ) signatures.
To summarize briefly:
A signature is a written response from the Imam (AJ) to questions posed to him, and it may also be issued without a preceding question, as is evident in some of them.
This term may specifically refer to what has been issued by the Imam of the Time (AJ).
These signatures have great benefits and significant effects, of which we will mention two:
First: They clarify the principles of religion in all its fields and rulings, as is clear to anyone who examines them.
Second: They indicate his existence and that he is alive, as they are a trace of his effects, and an effect indicates the cause. This is a clear indication without any doubt or ambiguity.
(One final word)
As mentioned in some statements, some of these signatures are subject to discussion, acceptance, and rejection in the words of scholars regarding the authenticity of some of them and similar matters.
Others have been relied upon for various jurisprudential issues by the scholars of the Imami sect.
However, the status of the signatures regarding acceptance and rejection is similar to that of other noble narrations reported from the Imams of guidance (peace be upon them). They are subject to scientific scrutiny in verifying and evaluating their narrators or trusting their issuance. Each scholar has their own methodology (and these are topics discussed in the science of narrators).
If a signature meets the conditions of authenticity, it is accepted and acted upon; otherwise, it is treated like any of the reports from the pure Ahlul Bayt.
All praise is due to Allah, the Lord of the worlds.
And blessings and peace be upon our master Muhammad and his pure family.