What is the ruling on grouping many e-mail addresses into one list and sending e-mails calling them to the way of Allaah The Almighty without their permission?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

Da‘wah is among the best and most venerated acts of worship. Allaah The Almighty Says (what means): {And who is better in speech than one who invites to Allaah and does righteousness and says, "Indeed, I am of the Muslims."}[Quran 41:33]

The Prophet, sallallaahu ‘alayhi wa sallam, told us that if someone is the cause for guiding one single person to Islam, that is better for him than possessing the most precious wealth of this world. [Al-Bukhari and Muslim]  He also said that anyone who guides others to a good deed will gain a reward equal to that of those who do it. [Muslim]

Furthermore, the Prophet told us that anyone who calls others to follow guidance, his reward will be equal to all those who follow him without their rewards being diminished. [Muslim]

Da‘wah does not require permission. It should be done at every opportunity. Accordingly, it is permissible to group e-mail addresses into one mailing list and send Da’wah messages to their owners without their permission.

All that was said thus far is regarding emails that are published on the net and available to the public. However, it does not apply to private emails, as the permission and consent of such private emails must be sought before listing it in general mailing lists, because this transgresses their privacy with which you were entrusted (or anyone possessing their emails).

Allaah Knows best.