diff --git a/lib/mail/constants.ts b/lib/mail/constants.ts
index de7bf930..11cbb131 100644
--- a/lib/mail/constants.ts
+++ b/lib/mail/constants.ts
@@ -1,25 +1,25 @@
 export const MESSAGE_FLAGS = {
-    FLAG_RECEIVED: 1, // whether a message is received
-    FLAG_SENT: 2, // whether a message is sent
-    FLAG_INTERNAL: 4, // whether the message is between ProtonMail recipients
-    FLAG_E2E: 8, // whether the message is end-to-end encrypted
-    FLAG_AUTO: 16, // whether the message is an autoresponse
-    FLAG_REPLIED: 32, // whether the message is replied to
-    FLAG_REPLIEDALL: 64, // whether the message is replied all to
-    FLAG_FORWARDED: 128, // whether the message is forwarded
-    FLAG_AUTOREPLIED: 256, // whether the message has been responded to with an autoresponse
-    FLAG_IMPORTED: 512, // whether the message is an import
-    FLAG_OPENED: 1024, // whether the message has ever been opened by the user
-    FLAG_RECEIPT_SENT: 2048, // whether a read receipt has been sent in response to the message
+    FLAG_RECEIVED:      1 << 0, // whether a message is received
+    FLAG_SENT:          1 << 1, // whether a message is sent
+    FLAG_INTERNAL:      1 << 2, // whether the message is between ProtonMail recipients
+    FLAG_E2E:           1 << 3, // whether the message is end-to-end encrypted
+    FLAG_AUTO:          1 << 4, // whether the message is an autoresponse
+    FLAG_REPLIED:       1 << 5, // whether the message is replied to
+    FLAG_REPLIEDALL:    1 << 6, // whether the message is replied all to
+    FLAG_FORWARDED:     1 << 7, // whether the message is forwarded
+    FLAG_AUTOREPLIED:   1 << 8, // whether the message has been responded to with an autoresponse
+    FLAG_IMPORTED:      1 << 9, // whether the message is an import
+    FLAG_OPENED:       1 << 10, // whether the message has ever been opened by the user
+    FLAG_RECEIPT_SENT: 1 << 11, // whether a read receipt has been sent in response to the message
     // For drafts only
-    FLAG_RECEIPT_REQUEST: 65536, // whether to request a read receipt for the message
-    FLAG_PUBLIC_KEY: 131072, // whether to attach the public key
-    FLAG_SIGN: 262144, // whether to sign the message
-    FLAG_HAM_MANUAL: 1 << 27, // The message is in spam and the user moves it to a new location that is not spam or trash (e.g. inbox or archive).
-    FLAG_PHISHING_AUTO: 1 << 30, // Incoming mail is marked as phishing by anti-spam filters.
-    FLAG_DMARC_FAIL: 1 << 26, // Incoming mail failed dmarc authentication.
-    FLAG_UNSUBSCRIBED: 1 << 19, // Unsubscribed from newsletter
-    FLAG_SCHEDULED_SEND: 1 << 20, // Messages that have been delayed send
+    FLAG_RECEIPT_REQUEST: 1 << 16, // whether to request a read receipt for the message
+    FLAG_PUBLIC_KEY:      1 << 17, // whether to attach the public key
+    FLAG_SIGN:            1 << 18, // whether to sign the message
+    FLAG_UNSUBSCRIBED:    1 << 19, // Unsubscribed from newsletter
+    FLAG_SCHEDULED_SEND:  1 << 20, // Messages that have been delayed send
+    FLAG_DMARC_FAIL:      1 << 26, // Incoming mail failed dmarc authentication.
+    FLAG_HAM_MANUAL:      1 << 27, // The message is in spam and the user moves it to a new location that is not spam or trash (e.g. inbox or archive).
+    FLAG_PHISHING_AUTO:   1 << 30, // Incoming mail is marked as phishing by anti-spam filters.
 };
 
 export enum VERIFICATION_STATUS {