that sites sell Google suite free account. When google suite came out at first time a few years ago, they allow people to create a free google suite account with their own domain name. They will randomly get google suite account that allow to create 25,50,100,200,500,2000 account under their domain name. now this program is already stopped for a long time (
https://support.google.com/a/answer/2855120?hl=en ), but people who already got the account can still use their account.
at first time when they stop this google suite legacy free, we still can change domain name so some people start to selling their accounts. But gooungle stop this feature, we cannot change our primary domain name again also we cannot add additional domain name, we just can add domain alias. Some people found a loophole that they still can use to change the primary domain name, but when this method going public google patch this loophole.
so if you are going to buy google suite legacy free account, make sure your seller can help you change the domain name or you will stuck with the original domain name.
Is it safe to use google suite legacy free account ? from my experience it is safe as long as we not violate google terms. Back then I had 2 google suite legacy free account, 100 account and 500 account, i sold my 500 account google suite legacy free ( a bit cheaper because i don't know how to change the domain name so i just sell to the other seller not end user ) and still use the other one until now. Google never disabled my account until now. just be carefull when you buy google legacy free account with unlimited storage because google only give this for Education institute ( back the you need to have .edu domain name to get the unlimited storage account ), so i don't know what will happen when primary domain name changed from education domain to ordinary domain.
but if you afraid they will ban you someday then i suggest you to always have a backup ( download your e-mail using google imap or pop3 ) or just pay the commercial version of google suite. other alternative is office 365 ( business essential or business premium )
if you looking for free email, i think zoho and yandex still will give a free email with your own domain ( but i don't know the limit ). they also have commercial services.
if you looking for cheap mail server alternative, you also can try some provider such as mailcheap ( enterprise shared or enterprise dedicated ) or mxroute ( check their blogs for promotions ).
