diff --git a/app/views/layouts/mailer.html.erb b/app/views/layouts/mailer.html.erb
index a834777e2..cd7502ec1 100644
--- a/app/views/layouts/mailer.html.erb
+++ b/app/views/layouts/mailer.html.erb
@@ -55,6 +55,7 @@
         font-weight: 600;
         height: 2.75em;
         line-height: 2.75em;
+        mso-line-height-rule: exactly;
         overflow: hidden;
         text-align: center;
         width: 2.75em;