I would like to create an email server for sending email to potential clients
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I would recommend checking out these two articles:
https://www.digitalocean.com/community/tutorials/why-you-may-not-want-to-run-your-own-mail-server
https://www.digitalocean.com/community/tutorials/how-to-set-up-a-postfix-e-mail-server-with-dovecot
Of course you need to make sure that you are sending out emails to legitimate subscribers otherwise your account might be disabled if you try to send out spam.