requirements about encryption in email gateway?

Question

I have exchange servers with the email gateway solution, do I necessarily require a certificate on my servers? apart from being compatible with tls 1.2 encryption by enabling encryption.
I understand that sophos forwards encrypted incoming emails to the servers but in case internal users send encrypted emails, what is the process?

emmosophos · Answer

Hello Eder, 
 Thank you for contacting the Sophos Community. 
 These are the types of Encryption that Central Email offers: 
 
 Send via TLS . This uses push based email encryption using AES 256 during email transport. Users manage their encrypted emails with their usual email client. 
 Push Encryption . Encrypted emails are converted to PDF files and attachments are natively encrypted. These are delivered to the users' email client. 
 Portal Encryption . This delivers encrypted emails to Sophos Secure Message . Recipients manage their encrypted emails in Sophos Secure Message . 
 
 If you select Send via TLS you are correct you just need to enable TLS v1.2 with the following ciphers 'TLSv1.2+FIPS:kRSA+FIPS:!eNULL:!aNULL'. For more information. 
 But you don't need certificates on your Exchange server. 
 Regards,