diff --git a/RNMail/RNMail.m b/RNMail/RNMail.m
index e73737b..605c373 100644
--- a/RNMail/RNMail.m
+++ b/RNMail/RNMail.m
@@ -120,6 +120,8 @@ + (BOOL)requiresMainQueueSetup
                 mimeType = @"audio/flac";
             } else if ([attachmentType isEqualToString:@"ogg"]) {
                 mimeType = @"audio/ogg";
+            } else if ([attachmentType isEqualToString:@"xls"]) {
+                mimeType = @"application/vnd.ms-excel";     
             }
 
             // Add attachment