Server -> Client: +OK Dovecot ready. Server -> Client: +OK Server -> Client: -ERR [AUTH] Authentication failed.
Array
(
    [error] => Server reported an error: -ERR [AUTH] Authentication failed.

    [errno] => 0
    [errstr] => 
)
SERVER -> CLIENT: 220-gdgh4.goodsportsthailand.com ESMTP Exim 4.89 #1 Sun, 19 Nov 2017 10:06:34 +0700 220-We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail.
CLIENT -> SERVER: EHLO allnewisuzud-max.com
SERVER -> CLIENT: 250-gdgh4.goodsportsthailand.com Hello allnewisuzud-max.com [150.95.24.60]250-SIZE 52428800250-8BITMIME250-PIPELINING250-AUTH PLAIN LOGIN250-STARTTLS250 HELP
CLIENT -> SERVER: MAIL FROM:<from@example.com>
SERVER -> CLIENT: 250 OK
CLIENT -> SERVER: RCPT TO:<whoto@example.com>
SERVER -> CLIENT: 550-Please turn on SMTP Authentication in your mail client. 550-(allnewisuzud-max.com) [150.95.24.60]:50718 is not permitted to relay550 through this server without authentication.
SMTP ERROR: RCPT TO command failed: 550-Please turn on SMTP Authentication in your mail client. 550-(allnewisuzud-max.com) [150.95.24.60]:50718 is not permitted to relay550 through this server without authentication.
CLIENT -> SERVER: QUIT
SERVER -> CLIENT: 221 gdgh4.goodsportsthailand.com closing connection
SMTP Error: The following recipients failed: whoto@example.com
SMTP Error: The following recipients failed: whoto@example.com