A sender can use an existing X-header, listed in VTO as I’ll add a custom X-header. In the example below, ‘X-NSS:’ is used by Epsilon senders and ‘X=KMail-Message:’ is used by Klaviyo senders.
Check with your ESP to determine if there is an existing X-header you can use. If using an X-header isn’t an option, use one of the other campaign identifier methods.
Alternatively, a sender can insert a VTO-specific X-header, listed in VTO as Generate an X-header for me: “X-VTO-Campaign: <value>”. The <value> is assigned during campaign set up. In the example below, X-VTO-Campaign is the VTO specific X-header.
Check with your ESP to determine if you can insert the VTO-specific X-header. If using an X-header isn’t an option, use one of the other campaign identifier methods.
Campaign subject line
You can select to have all email matching a specific subject to be optimized through VTO delivery as long as the DKIM domain and selector also match. This option is listed in VTO as Use the email’s subject line. Please provide the exact subject string when provisioning campaigns.
Emojis, other special characters, and personalization might result in issues. If your subject line includes special characters, the subject line option will not appear and you should use one of the other campaign identifier methods.
You can embed additional code into your HTML templates to indicate that an email should be optimized through VTO. The script for the body tag is leveraging the schema.org standard.
The script to be added is: