Unable to send, receive, and login to email. Using Roundcube, ISPConfig, Proxmox.

[djmixx07]

Hi everyone, embarrassingly speaking..I am a complete newbie when it comes to Linux and server administration. I am trapped in a situation in my current work that all was turned over to me when our network administrator resigned. I work at a government office here in the Philippines.

So here goes the problem. Our email (neither Roundcube or Thunderbird) is unable to send and receive emails. I am also unable to login to Roundcube. It just loads for a while after logging in then goes to the next page which is just a plain white page. Upon checking in ISPConfig, all the servers are online, specially POP3 and SMTP.

So I just can't figure out whats going on, and what's wrong with it. It was working perfectly last week. Then just broke down all of a sudden. I did series of shutdowns and restarts at our 2 baremetal servers..but to no avail.
I am not sure if it's about postfix because when I do "/etc/init.d/postfix restart", it says that it's already running.. But when I do "/etc/init.d/postfix status", it says it's not running..which is very confusing as well.

I really hope for your help guys. I would greatly appreciate any assistance. Thanks in advance.

PS:
Since I am a complete novice in Linux, if you can assist also in what command to type in terminal..I would REALLY appreciate it.

Kindly,
DJ