Apostolic Constitution compiled c. 390:
7.431 - Ordain also a deaconess who is faithful and holy for the ministrations towards women for sometimes the bishop cannot send a deacon (who is a man) to the women, on account of unbelievers. You should therefore send a woman, a deaconess, on account of the imaginations of the bad. For we stand in need of a woman, a deaconess, for many necessities. For example, in the baptism of women, the deacon will anoint only their forhead with the holy oil. And after him, the deaconess will anoint them. For there is no necessity that a woman should be seen by the men.
7.494 - A deaconess does not bless, nor does she perform anything belonging to the office of presbyters or deacons. Rather, she is only to keep the doors and to minister to the presbyters in the baptising of women, for the saake of decency.
7.410 - Let not any woman addresss herself to the deacon or bishop without the deaconess.
7.457 - Let the deaconess be a pure virgin. Or, at the minimum, let her be a widow who has been married only once and who is faithful and well esteemed.