All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
It is not forbidden to publish what the deceased had written whether it is a message and the like, as long as what was included in those messages does not contain anything that contradicts the Sharee’ah. Rather, it is more appropriate to endeavor to publish them if it contains knowledge that is beneficial to others.
The Prophet said: “When a person dies, all his good deeds cease except for three: a continuous charity, knowledge from which people derive benefit, and a righteous child who supplicates Allah for him.” [Muslim]
Allah knows best.