Is it allowed for a man engaging a veiled woman to see her photo prior to marriage ?

It is permissible for the suitor to look at the woman he proposes to before marriage. This is based on the hadith narrated by al-Mughirah ibn Shu’bah (may Allah be pleased with him) wherein it is reported that he proposed to a woman and the Prophet (peace and blessings be upon him) told him: “Look at her because that is more likely to create love between you" [Recorded by Abu Dawud, At-Tirmdhi and An-Nasa'i].

Jabir ibn Abdullah (may Allah be pleased with them both) narrated that he heard the Prophet (peace and blessings be upon him) saying: "When anyone of you proposes to a woman, if he can look at that which will encourage him to go ahead and marry her, then let him do so” [Recorded by imam Ahmed and Abu Dawud].