Is it permissible to publish an email that includes a da'wah clip with the phrase "This email is an ongoing charity (Sadaqah Jariyah) for the reward of everyone who publishes it" within it?

There is no objection to publishing an email that contains useful da'wah (Islamic propagation) or scholarly material; it is among the acts of righteousness and goodness that are hoped to be an ongoing charity (sadaqah (definition) jariyah), due to the Prophet's (peace and blessings be upon him) saying: "Indeed, among what continues to reach a believer of his deeds and good works after his death is knowledge he taught and disseminated."