app/views/issued_certificate_mailer/issued.html.erb
<%
course = @issued_certificate.certificate.course
user = @issued_certificate.user
link = issued_certificate_url(serial_number: @issued_certificate.serial_number)
%>
<% content_for(:title_button_link, link) %>
<% content_for :salutation do %>
<%= t("shared.salutation_name", name: user.name) %>
<% end %>
<% content_for :body do %>
<p>
<b><%= t("mailers.issued_certificate.issued.body.congratulations") %></b>
</p>
<p>
<%= t("mailers.issued_certificate.issued.body.awarded_certificate_html", course_name: course.name) %>
</p>
<p>
<%= t("mailers.issued_certificate.issued.body.issued_on_html", issued_certificate: @issued_certificate.created_at.strftime('%b %e, %l:%M %p'), link_to: link_to(t("mailers.issued_certificate.issued.body.link_to"), link)) %>
</p>
<%= render 'mailers/link_fallback', url: link %>
<% end %>