SMTP server address: domain.tld
SMTP Port: 25
Authentication method for SMTP: Login
SMTP username: stats@domain.tld
SMTP password: *******
SMTP encryption: TLS

Apr 16 04:22:06 s1 postfix/smtpd[2106]: connect from s1.domain.tld[xx.xxx.xxx.xxx]
Apr 16 04:22:06 s1 postfix/smtpd[2106]: setting up TLS connection from s1.domain.tld[xx.xxx.xxx.xxx]
Apr 16 04:22:06 s1 postfix/smtpd[2106]: Anonymous TLS connection established from s1.domain.tld[xx.xxx.xxx.xxx]: TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)
Apr 16 04:22:06 s1 postfix/smtpd[2106]: NOQUEUE: reject: RCPT from s1.domain.tld[xx.xxx.xxx.xxx]: 504 5.5.2 <localhost>: Helo command rejected: need fully-qualified hostname; from=<noreply@domain.tld> to=<hello@domain.tld> proto=ESMTP helo=<localhost>
Apr 16 04:22:06 s1 postfix/smtpd[2106]: lost connection after RCPT from s1.domain.tld[37.221.195.121]
Apr 16 04:22:06 s1 postfix/smtpd[2106]: disconnect from s1.domain.tld[xx.xxx.xxx.xxx]

smtpd_tls_auth_only = yes

smtpd_helo_restrictions = permit_mynetworks,
    reject_non_fqdn_hostname,
    reject_invalid_hostname,
    permit

smtpd_helo_restrictions = permit_mynetworks,
    permit_sasl_authenticated,
    reject_non_fqdn_hostname,
    reject_invalid_hostname,
    permit