Create mailing list in Horde

You should do it from webmail. To do this, follow the following steps:

1- Enter your webmail from:

https://webmail.midominio.com.ar/

with your access credentials.

2- Once inside the account, click on "Address Book" found in the menu at the top.

3- On the left, click on the "+" sign to the right of "My address book". There you should create the list, for example "Friends".

4- Once the list is created, a "New Contact" item appears at the top left, click there.

5- There you must select the list where you are going to assign this contact, in this case we select the newly created list "friends".

6- In the "personal" tab we add your name and additional data, in the "communications" tab we add the email account.

7- Finally we click on the "add" button located at the bottom.

8- When we are going to send an email, in "for" we place "friends" and this mail will be sent to all the people who are in this group.