Mail signature (#485)

* added signature field -- no function yet

* added mail signature feature

* fixed style issue

* fixed problem with signature default

* added unit test for mail signatures

* added unit test for mail signatures

src/pretix/base/services/mail.py

@@ -114,6 +114,16 @@ def mail(email: str, subject: str, template: Union[str, LazyI18nString],
                 subject = "[%s] %s" % (prefix, subject)
 
             body_plain += "\r\n\r\n-- \r\n"
+
+            signature = str(event.settings.get('mail_text_signature'))
+            if signature:
+                signature = signature.format(event=event.name)
+                signature_md = signature.replace('\n', '<br>\n')
+                signature_md = bleach.linkify(bleach.clean(markdown.markdown(signature_md), tags=bleach.ALLOWED_TAGS + ['p', 'br']))
+                htmlctx['signature'] = signature_md
+                body_plain += signature
+                body_plain += "\r\n\r\n-- \r\n"
+
             body_plain += _(
                 "You are receiving this email because you placed an order for {event}."
             ).format(event=event.name)

src/pretix/base/settings.py

@@ -191,6 +191,10 @@ DEFAULTS = {
         'default': settings.MAIL_FROM,
         'type': str
     },
+    'mail_text_signature': {
+        'type': LazyI18nString,
+        'default': ""
+    },
     'mail_text_resend_link': {
         'type': LazyI18nString,
         'default': LazyI18nString.from_gettext(ugettext_noop("""Hello,

src/pretix/base/templates/pretixbase/email/plainwrapper.html

@@ -148,6 +148,18 @@
                 </td>
             </tr>
         {% endif %}
+	{% if signature %}
+            <tr>
+                <td class="gap"></td>
+            </tr>
+            <tr>
+                <td class="order containertd">
+                    <div class="content">
+                        {{ signature | safe }}
+                    </div>
+                </td>
+            </tr>
+        {% endif %}
         <tr>
             <td class="footer">
                 <div>