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Sorry to hear you’re facing problems 
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In order to help you as quickly as possible, before clicking Create Topic please provide as much of the below as you can. Feel free to use a pastebin service for logs, otherwise either indent short log examples with four spaces:
example
Or for longer, use three backticks above and below the code snippet:
Hello, I'm facing an issue or may be an ignorance in parameters & configuration
The user mail box is not reachable (always gray)
I Use the LDAP user and group backend V1.10.2
The configuration is ok and the authentication AD is good but in user parameters no AD mail box ?
So users cannot put their own mailbox and it's not set by the LDAP link.
Where dis I go wrong ?
Thks for any help & regards
PM Guyot/Don-Bosco
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version : Latest 20
Operating system and version : Debian 10/64bits
Apache or nginx version : Nginx 1.14.2-2+deb10u3
PHP version (eg, 7.1): 7.3
The issue you are facing: Cannot set user maibox (except in admin), field mail address is not link to AD LDAP thouh authentication is good
Is this the first time you’ve seen this error? (Y/N): Y
Steps to replicate it:
The output of your Nextcloud log in Admin > Logging:
PASTE HERE
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
PASTE HERE
The output of your Apache/nginx/system log in /var/log/____:
PASTE HERE