The “via” in Gmail is shown to notify the gmail users that they are seeing a non-authenticated email. This usually happens due to failures in SPF or DKIM signing or if you are using a different envelope subdomain for sending emails apart from the sender domain. 

In order to fix this issue, please verify your SPF configuration & configure a custom envelope record for your sender domain. Once done, you can let us know to sign your emails with DKIM signing so that we can get it done for you. Once done, you will not see “via” within your emails in Gmail.

In case of any further help required on this, you can buzz us on our 24X7 chat support for more details.