How do I Stop to receive mails for one account in local VPS?

[webstower]

Hi Everybody,

Im begginer using vestacp and have a problem, I will try to explain:

In the UBUNTU 16.x VPS have 2 sites, for this example will name them: A and B

The site A (sitea.com) use all the services in the VPS (web, mail, ftp, etc)
The site B (siteb.com) use all the services in the VPS except the mail service that use GSuite
The MX records from the DNS zone for the site B points to GSuite..

Now, in the site A (sitea.com) we have a wordpress site with contact form that sends de filled form by mail to userx@siteb.com

The userx@siteb.com nevers get that mail in Gsuite... But if I access to the roundcube of the userx@siteb.com thats reside locally in my VPS.. the mails is there..

Following the DNS records that are configured to siteb.com
siteb.com..........MX..........1..........aspmx.l.google.com.
siteb.com..........MX..........10..........alt4.aspmx.l.google.com.
siteb.com..........MX..........10..........alt3.aspmx.l.google.com.
siteb.com..........MX..........5..........alt2.aspmx.l.google.com.
siteb.com..........MX..........5..........alt1.aspmx.l.google.com.
mail._domain..........TXT.........."v=DKIM1; k=rsa; p=blablabla..."
_domainkey..........TXT.........."t=y; o=~;"
_dmarc..........TXT.........."v=DMARC1; p=none"
@..........TXT.........."v=spf1 a mx ip4:myserverip ~all"
imap..........A..........myserverip
pop..........A..........myserverip
ftp..........A..........myserverip
mail..........A..........myserverip
smtp..........A..........myserverip
www..........A..........myserverip
@..........A..........myserverip
@..........NS..........ns2.domain.tld.
@..........NS..........ns1.domain.tld.

Why the mail sended by the sitea.com aren´t routed to the userx@siteb.com that resides in the Gsuite ?

Can anyone help with this problem?

Thanks in advance!