case-insensitive authentication in postfix-mysql

Just a quick note. If you find that your customers can log into their postfix account ok, but can’t read their email, check the directory their email is in:

[root@postfix /]# cd /home/vmail/domainname.ie/
[root@postfix domainname.ie]# ls -l
drwx------  5 postfix postfix 4096 Sep  4 11:52 joe.smith
drwx------  9 postfix postfix 4096 Sep  9 09:30 jane.smyth
drwx------  9 postfix postfix 4096 Sep  9 21:09 Jane.Smyth

The problem appears to be that postfix authenticates using MySQL, which is case-insensitive by default, then creates a default email skeleton directory named after the login username if it doesn’t find one already.

You can see in the above example that our user has logged in using uppercase letters in the username, MySQL verified the user had a right to be there, then postfix created the user’s directory using the login credentials, even though a lower-case version of the directory name already existed…

Obviously, this incorrect account will not receive email – email will be sent to the correct one.

There are a few solutions:

  • you can remove the Jane.Smyth directory and tell the user to change their authentication to use a lowercase username.
  • you can remove the Jane.Smyth directory then create a symbolic link from jane.smyth to Jane.Smyth.
  • change your MySQL installation to use a case-sensitive collation.

Personally, i go for the first solution.

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