Enabling TLS in Postfix

Hey guys!

I'm facing some issues to set up TLS in Postfix. With my current config I can set up a mailbox in Outlook, for example, using Port 465 with SSL/TLS selected. But if I try 587 I can only get it to work if I select STARTTLS.

And when I try to use Gmail to connect to this same mailbox using 587 port, I get this:
https://i.imgur.com/nPHjZAO.png

While using 465 with either SSL or TLS selected, I get this:
https://i.imgur.com/D0AWWpj.png

This is my main.cf file:

smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions = permit_mynetworks,    permit_sasl_authenticated,    reject_invalid_hostname,    reject_unauth_pipelining,    reject_unauth_destination,    ,    check_client_access hash:/etc/postfix/rbl_override,    reject_rhsbl_helo dbl.spamhaus.org,    reject_rhsbl_reverse_client dbl.spamhaus.org,    reject_rhsbl_sender dbl.spamhaus.org,    permit_dnswl_client list.dnswl.org=127.0.[0..255].[1..3],    permit_dnswl_client dnswl.spfbl.net,    reject_rbl_client zen.spamhaus.org,    reject_rbl_client b.barracudacentral.org,    reject_rbl_client cbl.abuseat.org,    reject_rbl_client bl.spamcop.net,    reject_rbl_client dnsbl.spfbl.net
smtp_tls_security_level = may
smtp_tls_note_starttls_offer = yes
smtp_tls_mandatory_protocols = !SSLv2,!SSLv3
smtp_tls_protocols=!SSLv2,!SSLv3
smtp_tls_loglevel = 1
smtp_tls_session_cache_database = btree:/var/lib/postfix/smtp_tls_session_cache
smtp_tls_cert_file = /etc/postfix/postfix.cert.pem
smtp_tls_key_file = /etc/postfix/postfix.key.pem
smtp_tls_CAfile = /etc/postfix/postfix.ca.pem
mailbox_size_limit = 0
allow_percent_hack = no
milter_default_action = accept
milter_protocol = 2
smtpd_milters = inet:localhost:8891,local:/run/milter-greylist/milter-greylist.sock
non_smtpd_milters = inet:localhost:8891,local:/run/milter-greylist/milter-greylist.sock
smtpd_tls_cert_file = /etc/postfix/postfix.cert.pem
smtpd_tls_key_file = /etc/postfix/postfix.key.pem
smtpd_tls_CAfile = /etc/postfix/postfix.ca.pem
smtpd_use_tls = yes
smtpd_tls_security_level = may
smtpd_tls_auth_only = yes
smtpd_tls_mandatory_protocols=!SSLv2,!SSLv3
smtpd_tls_protocols=!SSLv2,!SSLv3
smtpd_tls_loglevel = 1
smtpd_tls_session_cache_database = btree:/var/lib/postfix/smtpd_tls_session_cache
message_size_limit = 104857600
header_size_limit = 104857600
smtpd_client_restrictions = reject_unknown_reverse_client_hostname permit_mynetworks permit_inet_interfaces
smtpd_sender_restrictions = permit_mynetworks permit_sasl_authenticated reject_unknown_reverse_client_hostname reject_unknown_client_hostname reject_unknown_sender_domain
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks permit_sasl_authenticated check_helo_access hash:/etc/postfix/helo_access reject_invalid_helo_hostname reject_non_fqdn_helo_hostname reject_unknown_helo_hostname
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination

And this is my master.cf:

smtp inet n       -       n       -       -       smtpd
  -o smtpd_tls_auth_only=yes
submission inet n       -       n       -       -       smtpd
  -o smtpd_tls_security_level=encrypt
  -o milter_macro_daemon_name=ORIGINATING
smtps     inet  n       -       n       -       -       smtpd
  -o smtpd_tls_wrappermode=yes
  -o milter_macro_daemon_name=ORIGINATING

This is my mail.log when I try a connection using 587 SSL/TLS

May 27 15:51:07 ns1 dovecot: imap-login: Login: user=, method=PLAIN, rip=my-ip, lip=server-ip, mpid=10100, TLS, session=
May 27 15:51:07 ns1 dovecot: imap(teste@mydomain.com): Connection closed (IDLE running for 0.001 + waiting input for 0.001 secs, 2 B in + 10+10 B out, state=wait-input) in=11 out=380
May 27 15:51:07 ns1 postfix/smtpd[10104]: warning: database /etc/postfix/rbl_override.db is older than source file /etc/postfix/rbl_override
May 27 15:51:09 ns1 postfix/smtpd[10104]: warning: hostname my-ip.user.myisp.com.br does not resolve to address my-ip: Name or service not known
May 27 15:51:09 ns1 postfix/smtpd[10104]: connect from unknown[my-ip]
May 27 15:51:09 ns1 milter-greylist: smfi_getsymval failed for {daemon_port}, using default smtp port
May 27 15:51:09 ns1 postfix/smtpd[10104]: lost connection after UNKNOWN from unknown[my-ip]
May 27 15:51:09 ns1 postfix/smtpd[10104]: disconnect from unknown[my-ip]

But there's no log when I try to connect using Gmail webmail.
This is probably due to a reject_invalid_hostname, but I had to do this to prevent massive spam that my server was getting. But I can't understand why Gmail doesn't log to my mail.log so I can identify the problem.

All related ports are open in my firewall CSF (25,465,587).
Everything else is working (I can receive mails encrypted, I can send mails if I use Starttls or localhost using webmail, etc), this is the only issue I'm facing related to mail.

Can someone help me figure it out?

Thanks!