Often it is difficult for ISPs to block spam to everyone. This is because the ISPs do not know which email items you want to receive and which ones you do not. The ISP cannot predict in advance what email you have an expectation of getting and from where. It would also be inappropriate for ISPs to screen the content of the messages. There would also be privacy issues. However, there are certain approaches that can be taken at the email server side. If you have recently installed Linux and are thinking of running your own email server, then you should carefully consider the problem of spam.
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