jurega on "[Plugin: WP Mail SMTP] Unauthorized login in my Gmail account and problems with plugin"

I have an email hosted on the hosting service in Slovenia.But i cannot send a test mail from it. I tried with many different settings but no luck. I also tried with my gmail accounts, but it also had problems. And i also recived an email from gmail that somebody tried to login into my account (somebody from Frankfurt), just five minutes after i insert my data into the plugin.

I always recive following data, when i want to login with my hosted email info@copatekupi.si:

The SMTP debugging output is shown below:
SMTP -> get_lines(): $data was ""SMTP -> get_lines(): $str is "220 b2.hitrost.net ESMTP
"SMTP -> get_lines(): $data is "220 b2.hitrost.net ESMTP
"SMTP -> FROM SERVER:220 b2.hitrost.net ESMTP
CLIENT -> SMTP: EHLO *.copatekupi.si
SMTP -> get_lines(): $data was ""SMTP -> get_lines(): $str is "501 Syntactically invalid EHLO argument(s)
"SMTP -> get_lines(): $data is "501 Syntactically invalid EHLO argument(s)
"SMTP -> FROM SERVER:501 Syntactically invalid EHLO argument(s)
SMTP -> ERROR: EHLO command failed: 501 Syntactically invalid EHLO argument(s)
CLIENT -> SMTP: HELO *.copatekupi.si
SMTP -> get_lines(): $data was ""SMTP -> get_lines(): $str is "501 Syntactically invalid HELO argument(s)
"SMTP -> get_lines(): $data is "501 Syntactically invalid HELO argument(s)
"SMTP -> FROM SERVER:501 Syntactically invalid HELO argument(s)
SMTP -> ERROR: HELO command failed: 501 Syntactically invalid HELO argument(s)
CLIENT -> SMTP: STARTTLS
SMTP -> get_lines(): $data was ""SMTP -> get_lines(): $str is "503 STARTTLS command used when not advertised
"SMTP -> get_lines(): $data is "503 STARTTLS command used when not advertised
"SMTP -> FROM SERVER:503 STARTTLS command used when not advertised
SMTP -> ERROR: STARTTLS command failed: 503 STARTTLS command used when not advertised
CLIENT -> SMTP: QUIT
SMTP -> get_lines(): $data was ""SMTP -> get_lines(): $str is "221 b2.hitrost.net closing connection
"SMTP -> get_lines(): $data is "221 b2.hitrost.net closing connection
"SMTP -> FROM SERVER:221 b2.hitrost.net closing connection

Thank you for help :)

https://wordpress.org/plugins/wp-mail-smtp/