still cannot send email

There was a problem while sending a test email. Related debugging output is shown below:

Versions:
WordPress: 4.9.4
WordPress MS: No
PHP: 5.5.38
WP Mail SMTP: 1.2.5

Params:
Mailer: mail
Constants: No

Server:
PHP.mail(): Yes
Please copy only the content of the error debug message above, identified with an orange left border, into the support forum topic if you experience any issues.