I have been receiving these SMTP errors for quite some time and coincidentally at the same time that the hosting servers were upgraded to VPN Plus. The upgrade was mandated by the server administrators if I wanted to use Composer. I believe without the VPN they saw Composer as a security risk. (over my head).
So basically this problem should be a no brainer. I have attached an image of my current settings. The domain name is neighbourhoodwatchshop.com.au so the SMTP Server name should be mail.neighbourhoodwatchshop.com.au right?
I have cleaned out both the SMTP User Field and the SMTP Password. To be crystal, both fields are empty and so now I wait for the next order to roll in and check for errors.
It still beggars belief why the SMTP user and password won’t work for me. I feel it may be more the server host than an OXID issue, but I just don’t know.
Something is quite strange and finally I have managed to get some techs with serious IT Skills who have been trying to sort it out too. They have managed to do a long list of things that I wasn’t even aware could be done.
Where we are at right now is: Error : SMTP Error: Could not connect to SMTP host.
I am happy to advise that my problem connecting to the SMTP host is now resolved and I thank those who shared some tips with me on how to remedy the problems.
In the end, leaving everything blank did not work for me and my Vers. 4 software and I suspect that it has more to do with the Server changes when my domain server was upgraded to VPS Plus and the extra security that goes with same. The [email protected] email address was white listed; permissions were corrected for the orders@ email; certain SMTP ports were opened for the specific cPanel user in the Firewall; and I must confess that some of these things I am not on top of however they seemed to do the trick. I am now 2 days free of any SMTP errors.