[CentOS] Sendmail is considered deprecated

Hello,

Today I searched redhat official portal and learned that Sendmail is considered deprecated. By default, CentOS 7 will use postfix as MTA. I need good advise on what it means to us. We are CentOS customers. We use that operating system for quite a few years. We rely on Sendmail for years for us to relay large quantity of emails to our customers for marketing purpose. We build our additional fallback servers as well for fallback relays. We build our customized configuration for Sendmail too. I really need help to figure out if we can continue using Sendmail (even deprecated) for future long term and what implication would be doing so.
Thanks,

- xinhuan