What can a user with write permissions do?

If the only thing your organization needs is for a user to be able to anonymously write in a chat group, you can give them exclusive writing permissions. 

Having writing permissions implies being able to: 

• Write with the group's avatar, instead of with their own user. The messages written by this user will be anonymized; they will appear with the name and icon of the group (e.g. Human Resources) instead of with their personal identity. 
• In read-only groups, they can write messages and share files.
• They can edit or delete their own messages or those written by other administrators with the group's avatar. The messages will be marked as "Edited" or "Deleted".