The public user doesn't have an email address.
To start a livechat conversation, the email of the user that start the
conversation is used. As the conversation was started in sudo,
the system user's email address was used.
But, since changes with sudo() and with_users(),
the public user is not able to start a livechat conversation
as the system email is not used anymore in this case as sudo is not
changing the user but only skip the user's access right.
To start a livechat conversation, and to post a message, at least
email_from must be filled in.
Anonymous name is used to fill in email_from to bypass the checks
and to build the author given back the thread window.
If anonymous name is empty, we fallback on the company's catchall email
from the mail.channel create user.
Pre-required for task ID: 2028059
Fix Task : 2037048
PR #34918
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>