The following question was put to the marja`.
In the case where the husband left the wife and the maintenance no longer comes – while the wife for the past five years has known nothing of his whereabouts – is it permitted for the woman to know re-marry as she has not heard from the husband since he left?
The marja`, Imam `Abdur-Rahman Ash-Shami, may Allah preserve him, gave the following reply,
The woman should raise her case to the Qadi of the area, seeking dissolving of the marriage on account of either 1) lack of maintenance or 2) her husband being absent for a long period of time.
It is then for the Qadi to make the decision on whether to dissolve the marriage or not. If he gives the ruling in favour of the dissolving, then she goes into her waiting period (Ar. `iddah) from the moment the marriage was pronounced dissolved. After this point, she may then re-marry.
If the woman in question has not done this, she still remains under the government of her husband, so she may not remarry until the marriage to the first husband is dissolved or ended.
Taken from the website of the maraji`.