#メール送信用のパラメータ
p3_lkid : Related To retURL ? Return URL if cancel is pressed
p2_lkid : To (Contact or Lead ID)
p3 : Related to name (input text)
p4 : CC
p5 : BCC
p6 : Subject
p23 : Email Body
p24 : Additional To template_id ? ← 間違えている？ 正解はこっちSalesforce Email Template ID
p26 : From Email Address
separate with semicolons is right
p24={!WF_Outreach_Version__c.Project_Manager_Email__c}+;+{!WF_Outreach_Version__c.Listening_English_Email__c}