Is it permissible to accept gifts from the marriage officiant who performs the marriage contract?

If the marriage official (ma'dhun) receives a salary from the public treasury, then it is not permissible for him to take money from those for whom he solemnizes the marriage. However, if he is a volunteer and is given something without asking for it, there is no harm in that. But if he is given something after asking for it, that is not preferable.