IMAP error when activating mail tab on group with dovecot plugin

Description

error message when I activate mail on a posix group :

... : Can not authenticate to IMAP server: [CLOSED] IMAP connection broken (authenticate)

Distribution Name and Version

Centos7

FusionDirectory Version

1.3-fixes

Plugin with the defect

dovecot

PHP version used

7.1

Origin of php packages

from https://integration.fusiondirectory.org/repos/fixes-releases/rpm/rhel/7/fusiondirectory-13-fixes/RPMS/

Steps to Reproduce

1. configure dovecot services on mail server (in system settings)
2. activate mail on posix group with mail address and mail server
3. validate data => error!

Expected behavior:

nothing. I don't want an imap connexion with mail group, only for mail user

Imap connection, so error, for mail group

100%

Additional Information

I use dovecot module for user mail quota.