Gmail Feedback Loop ID

Gmail requires that you insert a Feedback-ID header as a prerequisite to
using their Feedback Loop.

You can configure Studio to create this header for emails sent to @gmail.com
subscribers by writing your desired
SenderID to the
/var/hvmail/control/studio.gmail.feedback-senderid file. For example:

echo example-test > /var/hvmail/control/studio.gmail.feedback-senderid

This will cause Studio to insert a Feedback-ID header in the following format,
given that OrganizationID=13, CampaignID=32, SenderID=example-test:

Feedback-ID: o13:o13c32::example-test

For autoresponders, this header be in the following format, given that
OrganizationID=13, AutoresponderID=47, SenderID=example-test:

Feedback-ID: o13:o13a47::example-test

If the first line of /var/hvmail/control/studio.gmail.feedback-senderid is
blank, or if the file does not exist, then this header will not be written.