Plaintext authentication when using SSL/TLS encryption

Sep 4, 2016
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Greece
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Root Administrator
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Hello,

I am using Thunderbird as mail client and Dovecot as IMAP Server. I have the following settings in Thunderbird:

thunderbird_settings.png

When Thunderbird connects to dovecot IMAP Server i have the following line in /var/log/maillog:

Code:
Jan 18 00:28:56 server dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=xxx.xxx.xxx.xxx, lip=xxx.xxx.xxx.xxx, mpid=14654, TLS, session=<0PtxXwBjkM0uZ+lu>
What concerns me is the method=PLAIN message in the log file entry.

Is it safe to assume that the password is transfered encrypted from the client to the server as the whole connection is encrypted?

Do i miss something?
 
Last edited:

cPanelMichael

Administrator
Staff member
Apr 11, 2011
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Hello,

Dovecot documents the PLAIN method at:

Authentication - Dovecot Wiki

Note you can set the following option to "No" in "WHM Home » Service Configuration » Mailserver Configuration":

Allow Plaintext Authentication (from remote clients)

Per it's description:

This setting will allow remote email clients to authenticate using unencrypted connections. When set to “no”, only connections originating on the local server will be allowed to authenticate without encryption. Selecting “no” is preferable to disabling IMAP in the Protocols Enabled section since it will force remote users to use encryption while still allowing webmail to function correctly.

Check to see if Thunderbird still works properly after setting this option to "No".

Thank you.
 

cPanelMichael

Administrator
Staff member
Apr 11, 2011
47,909
2,222
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Is my password encrypted when i use SSL/TLS Option in Thunderbird?

Regardless of how Dovecot is configured.
Yes, as long as you are configuring it to use the TLS/SSL ports and SSL/TLS is selected (as indicated in your screenshot), the authentication details are encrypted during the transmission. The following Dovecot document explains this further:

Authentication/Mechanisms - Dovecot Wiki

Thank you.