You are cruising along and everything is working fine when suddenly you attempt to login to an email account via squirrelmail, horde, webmail, or roundcube and you are getting a 500 internal server error message. Your email client is suddenly not working and you need to access your email, so you do a web search for squirrelmail 500 internal server error, or something of that nature which is associated with cpanel webmail.
First, settle down it may be a simple resolution. If you have more than 1 email account on the domain that is showing the server error message, try logging into other accounts to see if it is an isolated issue with one horde, squirrelmail, webmail, or roundcube account. Many people have found that it’s only one email address or it is limited to specific mailboxes. You could also attempt to login to a different domains email account. Determining these factors could significantly assist in determining the issue with why the server denied access to the webmail account.
I had this problem myself and the web was full of some helpful ideas, suggestions, and possible fixs for my logging into email conundrum. The first thing I did was restart my server, without thinking about the issue or doing any investigating. When the restart failed I decided to check another account on the same domain. No problem, I logged right into squirrelmail webmail without issue.
I was in the middle of watching a game that was a half-time when I discovered this issue. So after seeing that the login error was limited to a single squirrelmail email account, I went back to the game. Sometimes it’s good to move away from an issue a bit and give time for logic to smack one upside the head!
Suddenly I recalled the mention of cPHulk in one of the descriptions from the search results. I did another search and found that cPHulk brute force detection could lockout, or otherwise prevent login to an cpanel webmail account that some hacker had recently attempted to login to. This is one function that it is set up to protect.
So I return to my computer and login to my WHM server account. I go to security and then cPHulk brute force detection and click on the logs tab so I can see all the recent attempts of logging into webmail accounts. I discover that yes there were some recent attempts thwarted by cPHulk. Then the big key rang out like a bell, at the bottom, where the most recent login attempts were logged, there was no IP address associated. In looking at the times I realized that those log listings were my attempts as I had whitelisted my IP with cPHulk previously.
The 500 error code coming from the server on my email login attempts was due to the fact that the squirrelmail webmail account was locked by cPHulk brute force detection. Now for the fix, I quickly copied the log files to a spreadsheet so I could keep the IP addresses of all those infringements. I removed all but the IP addresses and then saved the file as a text file. I then copied those IP addresses and pasted them into my current cPHulk brute force detection blacklist and saved it. This was to block out the current webmail account offenders as well as others.
Finally the last stage of the fix for the 500 internal server error for cpanel webmail. This fix required one click, it simply required a flushing of the cPHulk logs from within the WHM control panel, done. Of course, I went back and checked the squirrelmail user account that I received the 500 internal server error code from, and wah lah, my webmail account issues were resolved. I hope this will assist some folks out there in obtaining fixes for the 500 internal server error message when trying to log into any cpanel webmail accounts such as roundcube webmail, horde, or squirrelmail.