Every person wants to get rid of junk mail and spam mail, except spammers. To many users, it is a real nuisance as it hides important mail. For the web hosts, it blocks their resources, and for security professionals it implies more monitoring and filtering. Website owners find junk and spam mail carriers of malware and viruses. Whichever, your side is you do not benefit from spam, you are against it. How are you going to fight spam and how can it be attacked?
Studies have shown that a lot of spam and junk mail can lead to loss of other mails.
Blocking outgoing spam
It is the duty of web hosts to curb spam mail. This is because they are the 
destination and source of the emails. They have got adequate powers to plug the source and prevent emails from flooding the internet. It is possible to put security measures to ensure users get the only genuine mail. Usually, legitimate mail servers are the targets of hacking. They are then hacked, and emails pumped through them.
Reporting
If you are a victim of this, it is necessary to report to the hosting company. Web hosting companies do participate in reporting suspicious networks and addresses that are known to be sources of spammers or spam. The log stored by hosting companies can be shared with government and centralized private agencies. This will help others also benefit from the information. The things that are discussed include geographic patterns, targeting strategies, type of mail content, and spam patterns.
Restricting clients
A way of restricting spam is limiting the number of mails a user can send out once or in a given period. In fact, genuine users do not burst out emails and will rarely hit the limit set by the provider. The other way is to look at the delivery rate of emails sent out. For instance, if less more than 50% emails are delivered, the user can be considered as a spammer. This will help curb spammers that are using outdated mail lists.
Terms of service
These need to be very strict. It should be clear that they will not accept spam mail or unsolicited mailing. These are good conditions, which act as warnings to potential spammers. Protecting users of mail hosting users is important. People want to get only mails that are intended to them and not junk mail.