Error 200 in configuring SMTP

[agcool18]

I have been using EspoCRM at 4-5 places but never faced this problem before. When i'm trying to configure SMTP in the crm and then sending email i received error 500 so i thought it might be a permission problem and then i changed the permissions of some directories. Now i'm receiving error 200 while sending a test mail
Also check error log but not found anything unusual

I HAVE A VPS
Any help will be appreciated...


Thanks