Note: Benchmark Email does not advocate adding a contact's first name in the subject line of your emails. Doing so may lead to an increase of spam complaints, as spammers are known for using personal data in the subject line of emails.

If you want to personalize the subject lines of your email, you would have to use the construct [contact_attribute:FieldName] where FieldName refers to the field name

For example:
"[contact_attribute:firstname] check out our new products,"
If James Anderson receives your email, it will say: "James check out our new products" in the subject line.

You can go to the 'preview' and check if the contact details are replaced. If the contact detail does not exist, the field will appear blank.

Some of the common tags would be
[contact_attribute:firstname]
[contact_attribute:lastname]
[contact_attribute:email]
or [contact_attribute:FIELDLABEL] where FIELDLABEL is the label of the field used in the contact list. To get the labels you can go to the detail of any contact and copy-paste the label e.g "Job Title" or "Business Phone" etc. These would translate into [contact_attribute:Job Title] and [contact_attribute:Business Phone]

Personalization will not show up in test emails because there is no reference to specific contact details. You can send your email campaign to a small set of contacts if you’d like to test your personalization.