Is it permissible for Maria the Coptic and other concubines of the Messenger (may Allah's peace and blessings be upon him) to marry after his death?

It is forbidden to marry any woman with whom the Prophet, may Allah bless him and grant him peace, had intercourse, whether she was a wife or a slave-girl. This is one of his unique characteristics. Mariyah, the mother of Ibrahim, may Allah be pleased with her, was a slave-girl, and scholars have unanimously agreed on the prohibition of marrying her after the death of the Prophet, may Allah bless him and grant him peace.