1,346. Leading the Service

210:5 A mourner during the week of shiva should not lead the prayer service unless there is no one else available who is able to do so. However, if he is mourning for his father or mother, our practice is for the mourner to lead the service even if there is someone else present who could do so. On Shabbos and yom tov, the practice is for the mourner not to lead the service for the whole year unless no one else is able. If he typically led the service before becoming a mourner, there is reason to act leniently in the matter.

210:6 The rule concerning greetings is as follows: for the first three days, the mourner may not greet anyone. If he is greeted by someone who doesn't know that he's a mourner, he shouldn't respond. Rather, he should simply inform the one who greeted him that he is a mourner.  After the third day, through the end of shiva, the mourner may not greet someone but if he is greeted by others who don't know that he's a mourner, he may respond.

After shiva through the end of shloshim, he may greet others since they may receive greetings. Others should not greet him because he may not receive greetings. If they didn't know that he was a mourner and greeted him, he may reply. After thirty days, he is like anybody else in this regard.