An instructor has a learner in the class that needs to frequently check and reply...

Dismiss the learner from the class as they are not focused on the material.

Ask the learner to dismiss themselves from the class when they need to check and reply to email.

Inform the learner that their action is inappropriate and they need to check their email only during breaks.

Ask the learner to take the necessary steps to cause the least distraction to the rest of the class.