Control Web Panel
WebPanel => E-Mail => Topic started by: anandmys on December 08, 2025, 08:22:10 AM
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Logged in to user control panel. Use auto login to roundcube
Email 1 - Try sending email I get the error "Connection Error (Failed to reach server)"
Other 9 email ids works flawlessly
Please suggest
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Error logs say
[05-Dec-2025 11:05:13 +0000]: <g9kaaxsd> IMAP Error: Login failed for user@dom
ain.tld against localhost from 127.0.0.1 (X-Real-IP: 59.93.x.y,X-Forwarded-F
or: 59.93.x.y, 59.93.x.y). AUTHENTICATE PLAIN: Authentication failed. in /
usr/local/cwpsrv/var/services/roundcube/program/lib/Roundcube/rcube_imap.php on
line 211 (POST /?_task=login&_action=login)
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Make sure you have the IMAP option enabled when you built PHP.
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If it's automated login from the panel, should be using an API key to authenticate. Could be an odd gremlin. Try logging out/logging back in. Or could be some specific problem with the account. Can you test logging in manually? Are you able to reset the user credentials without interrupting customer access?
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Also what version of PHP and OS are you running?
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Strangely, this is happening to only 1 email id out of 100s of emails across multiple domain names.
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Try to reset the password for the problematic mailbox. Don't use the chars like "!@#%^&" because it could cause problems in some cases.
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The email had a plain signature
Thanks
Firstname lastname
Removing the signature, email is going.
Changing password didnt help
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Try again with your signature & check your Mod security logs, might need to disable one or two rules.
From CWP menu
Security > Mod Security & cick on logs
I had similar issue ages ago & Mod security was denying emails from Roundcube that had anythig more than a few words in the email (was only with Roundcube, all mail from other mail clients worked fine).
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Thank you. It was mod security issue.
There were issues with mod security paths and the file where I was adding the exception rules
Try again with your signature & check your Mod security logs, might need to disable one or two rules.
From CWP menu
Security > Mod Security & cick on logs
I had similar issue ages ago & Mod security was denying emails from Roundcube that had anythig more than a few words in the email (was only with Roundcube, all mail from other mail clients worked fine).
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If you are running OWASP CRS you can disable the global rule IDs 981176 and 949110.
Or add the following to your whitelist before the rules load:
SecRule REQUEST_URI "@contains /roundcube/" "id:{some number},phase:1,nolog,allow"
SecRule REQUEST_URI "@contains /roundcubemail-*/" "id:{some number},phase:1,nolog,allow"
Also if you send files you might have to disable certain file extension rules.
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NOTE: The {some number} mentioned above would use whatever number sequence you are using for custom rules.