You can use [`create mask`]( and [`directory mask`]( configuration option to configure more permissive umask to allow group members (or everyone) to modify files.

For example:

    create mask = 0775
    directory mask = 0775 

There are also respective [`force crate mode`]( and [`force directory mode`]( options. When used the respective permissions are always added to the files.

Depending on how your users are configured:

* If all your users share a common primary group, using above options is sufficient.

* In case the primary groups aren't shared, but users are members of common group, set the directory group to the common group and apply [*setgid bit*]( to it. When *setgid bit* is set to a directory, new files created inherit the directory's group and new directories created will have the *setgid bit* set as well.

* Use [*POSIX Access Control Lists*]( To enable ACL for a file system, you might need to use `acl` mount option. When default ACL is set for a directory, new files and directories created inherit the default ACL. See this answer for [how to inherit group permissions in Linux]( for details.