Issue with HC ticketing system and SPF

Friends,

I found some customers are rejecting ticketing emails due to SPF. Let me explain, their email is setup as lets say customer@domain.com.
 
When they open a ticket, they get a copy and the FROM/SENDER is their own email address customer@domain.com. When received by their remote SMTP (their ISP), it is rejected due to SPF failure.
 
I dont have access to domain.com. Its their "big ISP's" e-mail server, not their own domain.
 
Resadmin replies are ok as they use a static sender I define in HC. Problem seems to be with the copy they get of the ticket they opened, where HC uses FROM and TO = their profile address.
 
Pls advise if you guys can change the FROM in such cases or let us do that, to avoid SPF issues. Sorry if there's a setting for this, but seems there isnt.
 
Thanks.
 

Please, any news? Tahir, please, if HC can be just a bit more active in forum... Seems they leave everything just for you to answer... :(

See below... Pls, is there a way to change the SENDER? HC puts the sender the same email as receipient (customer's email) and thus many systems refuse it.
 
example:
 
187.73.32.156   [000A4588] 10:32:05 Client session >>> MAIL From:< xxx@advmail.com.br> SIZE=7226
187.73.32.156   [000A4588] 10:32:06 Client session >>> RCPT To:< xxx@advmail.com.br>
187.73.32.156   [000A4588] 10:32:34 Client session <<< 554 5.7.1 < xxx@advmail.com.br>: Sender address rejected: sender address is forged
 
Thanks.