Obfuscate it wherever possible.
For example, use contact forms on your website rather than just displaying your email address in clear text. This helps prevent spammers & web-crawling bots from spotting your address & adding it to the spammers databases.
A bad one is when you register your site & use your real email address in the form. Depending on what country you are in/ what extension you are registering, you may be obliged to have your details show up in the Whois - especially if you are a registered company rather than a private individual.
I used an email address to register a domain years ago, & even though I never used that email address anywhere else, it now gets loads of spam. This shows that the spammers are harvesting details from the Whois register, even though they are not supposed to be allowed to.
So either use a separate email address for the reg process, which you don't mind receiving junk in, or make use of the registrar's Privacy service. They often charge extra for this though. They then display their own contact details in the Whois, & only forward on the non-junk mail to you. I'm not sure exactly how this works.
There are also lots of really obvious tips which I won't go into great detail about here, such as ensuring your PC doesn't get viruses which could harvest your website's email address!
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