Error. I can not add more than one DistributionList to the recipients.

[msergv]

Hi.
WebApp: 3.4.0.878-566.1
Kopano Core: 8.4.90.238
CentOS7: php-5.4.16-42.el7.x86_64
I can not add more than one DistributionList to the recipients.
A method that does not work

1. We go to the “MAIL”.
2. Choose to create a letter.
3. In the address book, select the distribution groups. all exactly in what order.
   In the “To” field, only 1 distribution group is added. Only the first distribution group is always included.

PS:
My wife learn by specialty software tester.
It is practiced with the example of WEBAPP.
In what format should I send errors?
Where should I send the errors found?