Is marriage over the Internet valid if the offer and acceptance were in writing, with the presence of witnesses unknown to the wife, and the divorce was also in writing? Is this marriage valid, and what is the waiting period (iddah) resulting from it?

Marriage has conditions and pillars without which it is not valid according to Sharia (definition), such as the guardian, witnesses, offer, and acceptance. What transpired between the man and the woman through writing via the internet is a trifle, by which marriage is not concluded, and no consequences ensue from it. Therefore, she must sever her relationship with this man and repent to Allah Almighty.