[horde] Horde sending bulk mail

[michel at casa.co.cu]

Hello List

I'm new to the list as I notice horde beginner.

I have a problem and two questions.

It appears that this version use old horde is perhaps the reason for  
my problem, it is generating lot of email accounts outside of my  
domain such as yahoo and others.

My question

1 - how can I tell the version I'm using horde?
2 - how can I fix sending junk messages out of my domain?

Upgrading version ?

Sorry for my english , is very poor

Greetings

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Webmail, servicio de correo electronico
Casa de las Americas - La Habana, Cuba.