diff --git a/addons/mail/models/mail_message.py b/addons/mail/models/mail_message.py
index 3c17f207ab3..89e4237c8e1 100644
--- a/addons/mail/models/mail_message.py
+++ b/addons/mail/models/mail_message.py
@@ -28,7 +28,7 @@ class Message(models.Model):
     def _get_default_from(self):
         if self.env.user.email:
             return formataddr((self.env.user.name, self.env.user.email))
-        raise UserError(_("Unable to send email, please configure the sender's email address."))
+        raise UserError(_("Unable to post message, please configure the sender's email address."))
 
     @api.model
     def _get_default_author(self):
diff --git a/addons/mail/models/mail_thread.py b/addons/mail/models/mail_thread.py
index 73b2388329b..66dfcd84f8e 100644
--- a/addons/mail/models/mail_thread.py
+++ b/addons/mail/models/mail_thread.py
@@ -1998,16 +1998,16 @@ class MailThread(models.AbstractModel):
         kw_author = kwargs.pop('author_id', False)
         if kw_author:
             author = self.env['res.partner'].sudo().browse(kw_author)
-            email_from = formataddr((author.name, author.email))
         else:
             author = self.env.user.partner_id
-            email_from = formataddr((author.name, author.email))
+        if not author.email:
+            raise exceptions.UserError(_("Unable to log message, please configure the sender's email address."))
 
         message_values = {
             'subject': subject,
             'body': body,
             'author_id': author.id,
-            'email_from': email_from,
+            'email_from': formataddr((author.name, author.email)),
             'message_type': message_type,
             'model': kwargs.get('model', self._name),
             'res_id': self.ids[0] if self.ids else False,