If you have the list you can insert them directly into the database:
INSERT INTO elkarte_ban_items (id_ban_group, email_address)
VALUES (**BANGROUP**, '*.domain.xxx'),
(**BANGROUP**, '*.anotherdomain.yyy')
And so on, just make the list longer with the comma at the end of each line except the last one.
The only thin is find the bangroup, that you can find editing the ban and looking at the url, it should look like:
http://www.domain.tld/index.php?action=admin;area=ban;sa=edit;bg=2
that number at the end (2 in this case) is the bangroup, so the query above would become:
INSERT INTO elkarte_ban_items (id_ban_group, email_address)
VALUES (2, '*.domain.xxx'),
(2, '*.anotherdomain.yyy')