From Adress is displaying on behalf information

From Adress is displaying on behalf information

Hello,

I have a problem to set "from" address for e-mails sent form zoho desk - it always showing "on behalf" information like:  support=mydomain@eu-service.mailer.zohosupport.com; on behalf; Helpdesk IT <helpdesk@mydomain>

What I did:

-set "from" adres using my own SMTP server and verified e-mail adres (heldpesk@mydomain)
-enabled the address
-assigned the address to appropriate department
-changed "from adres" on templates and enabled them 

Still all communication (including automatic reply) is with "on behalf" information -  etc.

I will be grateful for any help in this topic.

Cheers