diff --git a/lib/message/mu-flags.cc b/lib/message/mu-flags.cc
index bd3e57e6..4668cb61 100644
--- a/lib/message/mu-flags.cc
+++ b/lib/message/mu-flags.cc
@@ -105,10 +105,13 @@ test_flags_from_expr()
 		      (Flags::Flagged | Flags::Unread |
 		       Flags::HasAttachment | Flags::MailingList));
 
+	/* note: unread is a special flag, _implied_ from "new or not seen" */
+	static_assert(flags_from_absolute_expr("N").value() == (Flags::New|Flags::Unread));
+
 	static_assert(!flags_from_absolute_expr("DRT?"));
 	static_assert(flags_from_absolute_expr("DRT?", true/*ignore invalid*/).value() ==
 		      (Flags::Draft | Flags::Replied |
-		       Flags::Trashed));
+		       Flags::Trashed | Flags::Unread));
 	static_assert(flags_from_absolute_expr("DFPNxulabcdef", true/*ignore invalid*/).value() ==
 		      (Flags::Draft|Flags::Flagged|Flags::Passed|
 		       Flags::New | Flags::Encrypted |
@@ -126,6 +129,16 @@ test_flags_from_delta_expr()
 	static_assert(flags_from_delta_expr(
 			      "+S-u-N", Flags::New|Flags::Unread).value() ==
 		      Flags::Seen);
+
+	/* note: unread is a special flag, _implied_ from "new or not seen" */
+	static_assert(flags_from_delta_expr(
+			      "+S-N", Flags::New|Flags::Unread).value() ==
+		      Flags::Seen);
+	static_assert(flags_from_delta_expr(
+			      "-S", Flags::Seen).value() ==
+		      Flags::Unread);
+
+
 	static_assert(flags_from_delta_expr("+R+P-F", Flags::Seen).value() ==
 		      (Flags::Seen|Flags::Passed|Flags::Replied));
 	/* '-B' is invalid */
@@ -134,7 +147,7 @@ test_flags_from_delta_expr()
 	static_assert(flags_from_delta_expr("+R+P-B", Flags::Seen, true) ==
 		      (Flags::Replied|Flags::Passed|Flags::Seen));
 	static_assert(flags_from_delta_expr("+F+T-S", Flags::None, true).value() ==
-		      (Flags::Flagged|Flags::Trashed));
+		      (Flags::Flagged|Flags::Trashed|Flags::Unread));
 }
 
 /*
diff --git a/lib/message/mu-flags.hh b/lib/message/mu-flags.hh
index 2ef1feb2..8675f00c 100644
--- a/lib/message/mu-flags.hh
+++ b/lib/message/mu-flags.hh
@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2022 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2022-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -225,10 +225,27 @@ flag_info(std::string_view name)
 	return Nothing;
 }
 
+/**
+ * 'unread' is a pseudo-flag that means 'new or not seen'
+ *
+ * @param flags
+ *
+ * @return flags with unread added or removed.
+ */
+constexpr Flags
+imply_unread(Flags flags)
+{
+	/* unread is a pseudo flag equivalent to 'new or not seen' */
+	if (any_of(flags & Flags::New) || none_of(flags & Flags::Seen))
+		return flags | Flags::Unread;
+	else
+		return flags & ~Flags::Unread;
+}
+
 /**
  * There are two string-based expression types for flags:
  * 1) 'absolute': replace the existing flags
- * 2_ 'delta'  : flags as a delta of existing flags.
+ * 2) 'delta'  : flags as a delta of existing flags.
  */
 
 /**
@@ -253,7 +270,7 @@ flags_from_absolute_expr(std::string_view expr, bool ignore_invalid = false)
 			flags |= info->flag;
 	}
 
-	return flags;
+	return imply_unread(flags);
 }
 
 /**
@@ -296,7 +313,8 @@ flags_from_delta_expr(std::string_view expr, Flags flags,
 		}
 	}
 
-	return flags;
+	return imply_unread(flags);
+
 }
 
 /**