It depends on the nature of the interaction, the intention, and purpose.
If it is halal for you to do it in person, face to face, in the same circumstances, then it is halal online.
If it is haram to be done in person, face to face, in the same circumstances, then it is haram online.

So, business conversation, discussion of Islam, group interaction for these purposes are okay.

But talking alone with opposite gender for socializing purpose, unless with intent for pursuing marriage under appropriate guidelines, may be ill-advised.

Salam and thanks for the interesting question. May allah guide us all.

Personally I have oline conversations with sisters but have now decided to not do so alone. Things might get too emotional(on either side) if it's a private conversation. I don't think this is very condusive to finding a mate for the sake of allah. I find there is blessing in having family members nearby. If a family member is not nearby I try to at least commit to showing a family member a copy of our interaction...for instance if sending an email you can just cc it to your brother or sister or whatever. This is not my fatwa. Just my personal approach which I hope someone may benefit from. I hope I don't mislead anyone by this.

After all that said I think islamic refernces of course are the most authoritative. So any light shed on this topic as per islamic references would be welcome in my book.

wassalamu alaikum and peace 2 u,
-anwar