In Odoo mass mailing module template, to render the contact name or other dynamic placeholder for fields, you need to use the mako expressions '${expr}' in the mail template. The placeholder token is different depending on the recipient object name.

When the Recipients type is Customer (fields of res.partner)

${object.name}

When the Recipients type is Applicant (fields of hr.applicant)

${object.partner_name}

When the Recipients type is Leads / Opportunities (fields of crm.lead) 

${object.partner_name} or ${object.contact_name}

When  the Recipients type is Mailing List (fields of mail.mass_mailing.contact)

${object.name}

Please Note: when you send the test email it is not rending the mako expressions.

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