Ao tentar executar telnet na porta 587 quando eu digito "AUTH LOGIN" a conexão é fechada ("Conexão fechada por host estrangeiro.") e tenho os seguintes logs em meu servidor postfix:
May 1 09:42:48 ip-172-31-44-68 postfix/submission/smtpd[30858]: connect from mx-ll-171.5.1-121.dynamic.3bb.co.th[171.5.1.121]
May 1 09:42:55 ip-172-31-44-68 postfix/submission/smtpd[30858]: SSL_accept error from mx-ll-171.5.1-121.dynamic.3bb.co.th[171.5.1.121]: -1
May 1 09:42:55 ip-172-31-44-68 postfix/submission/smtpd[30858]: warning: TLS library problem: error:0A00010B:SSL routines::wrong version number:../ssl/record/ssl3_record.c:354:
May 1 09:42:55 ip-172-31-44-68 postfix/submission/smtpd[30858]: lost connection after STARTTLS from mx-ll-171.5.1-121.dynamic.3bb.co.th[171.5.1.121]
May 1 09:42:55 ip-172-31-44-68 postfix/submission/smtpd[30858]: disconnect from mx-ll-171.5.1-121.dynamic.3bb.co.th[171.5.1.121] starttls=0/1 commands=0/1
Mudei os certificados, usei Let's encryptpara isso.
Como posso investigar mais detalhadamente esse problema para encontrar a causa raiz real?