Network Solutions email - spam issue

I work in a very small office and the last few weeks I've been getting a huge amount of spam emails (we use Network Solutions). Every one of them ends in either .eu or .in. Some examples: seheke.in, gidwo.eu, tigamuy.eu, cajiyup.eu....
I've tried to set up a custom filter, but they are always different suffixes and I just can't keep up. I'm the person in the office that everyone comes to with I.T. issues so there is no tech support here at all. There is also no way the owners would spend a dime on a firewall or something similar. Does anyone have a suggestion to block these emails? I don't have any clients in Europe so blocking anything ending in .eu is fine if needed.