How can one be an electronic da'ee (preacher/caller to Islam) without a legitimate religious certification, relying on the hadith "Convey from me even if it is a single verse," and is it permissible for him to transmit fatwas and lessons from scholars via online forums, and will he be rewarded for that?

Every Muslim should call people to Allah according to their ability and knowledge. It is not a condition to be a scholar; rather, it is sufficient to convey a verse or an issue that one has learned, based on the saying of the Prophet, peace and blessings be upon him: "Convey from me, even if it is a single verse." One can also transmit and disseminate the fatwas and lessons of scholars. Calling people to Allah and teaching them good brings immense reward, as Allah Almighty says: "And who is better in speech than one who invites to Allah and does righteousness and says, 'Indeed, I am of the Muslims,'" and as the Prophet, peace and blessings be upon him, said: "Indeed, Allah, His angels, the inhabitants of the heavens and the earths, even the ant in its hole and even the fish, send blessings upon the one who teaches people good."