My main email is an Earthlink account. It was being overwhelmed by spam with unusually large sizes, usually around 300KB. These contained large data blocks, presumable some kind software like tracking code.

I found I can eliminate almost all of them by blocking certain domains, using Earthlink's Blocked Sender List feature. I added the following to the list:

Four top-level domains:

.in
.loan
.us
.xyz

Four specific domain names:

info4tek.com
kabayaweb.com

proffbuilder.com
voip-info.org

I developed this list by marking the emails as spam, then looking at the sender addresses in the list Earthlink provides.

I'm sure additional ones will crop up in the future. I will just add them to the list, which can hold 500 entries. My current list is blocking about 60 spam emails per day, according to the daily report Earthlink sends me.

It is possible that some legitimate emails may be blocked, for example with the .us domain. I'm not sure, but I believe such addresses will pass through if you add them to your address book, at least with Earthlink.

Procedures for blocking with other email providers, if available, will probably be different.