There are four options available to identify a VTO campaign. You can match on subject line, existing X-header, VTO-specific X-header, or body tag, as long as the DKIM domain and selector also match.
Note: For any DKIM/campaign identifier pair, only one campaign can be active with the same DKIM details and campaign run times. You cannot have two campaigns running at the same time sharing the same DKIM details—with one using the X-header and another one using subject line, for example, or with both using the body tag. The exception is if your campaign identifier is the X-header and you use unique values for each key-value pair.
Example: You want to run an A/B test with the same subject line for each version, running at the same time. To successfully use VTO for this test, either you can use X-header as the identifier, with unique values for each version of the campaign, or you can send the two versions from different sending domains. Either option means your DKIM values are different.
Campaign subject line
You can select to have all email matching a specific subject line to be optimized through VTO delivery as long as the DKIM domain and selector also match. This option is the default for VTO. You can match on the exact subject line or only part of it.
- If you can provide the exact subject string when provisioning campaigns, select Exact Subject Line Match.
- If your subject line contains emojis, other special characters, or personalization, select Partial Subject Line Match.
- If your subject line is similar to another VTO campaign during the same time frame, VTO may have trouble differentiating the two campaigns. In that case, we recommend you use one of the other campaign identifier methods.
Subject: This is the best offer ever!
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.
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: