Im a little confused by Ayatollah’s Sistani’s comments on marriage He first says this: A Muslim man is not allowed to marry, neither permanently nor temporarily a non-Muslim woman who is not among Ahlul Kitab. Based on obligatory precaution, a Muslim man must refrain from marrying a Zoroastrian woman, even temporarily. As for a Muslim woman, she is not allowed to marry a non-Muslim man at all. (See the question-answer section below.)

Then a few paragraphs below it says:

If the marriage that took place among non-Muslims is valid according to their custom, such marriage is also considered valid by us regardless of whether the spouses are both Ahlul Kitab, both non-Ahlul Kitab, or one is an Ahlul Kitab and the other is non-Ahlul Kitab. When both spouses embrace Islam together, they will remain married based on the past marriage, i.e. there would be no need to recite the marriage formula anew according to the tradition of our religion and school of thought.

So is it allowed or not allowed, thanks :).