diff --git a/doc/man1/notmuch-insert.rst b/doc/man1/notmuch-insert.rst
index 47884515..86e2f567 100644
--- a/doc/man1/notmuch-insert.rst
+++ b/doc/man1/notmuch-insert.rst
@@ -51,6 +51,12 @@ Supported options for **insert** include
 ``--no-hooks``
     Prevent hooks from being run.
 
+``--world-readable``
+    When writing mail to the mailbox, allow it to be read by users
+    other than the current user.  Note that this does not override
+    umask.  By default, delivered mail is only readable by the current
+    user.
+
 ``--decrypt=(true|nostash|auto|false)``
     If ``true`` and the message is encrypted, try to decrypt the
     message while indexing, stashing any session keys discovered.  If
diff --git a/notmuch-insert.c b/notmuch-insert.c
index 48490b51..d229c9dc 100644
--- a/notmuch-insert.c
+++ b/notmuch-insert.c
@@ -159,10 +159,10 @@ mkdir_recursive (const void *ctx, const char *path, int mode)
  * otherwise. Partial results are not cleaned up on errors.
  */
 static bool
-maildir_create_folder (const void *ctx, const char *maildir)
+maildir_create_folder (const void *ctx, const char *maildir, bool world_readable)
 {
     const char *subdirs[] = { "cur", "new", "tmp" };
-    const int mode = 0700;
+    const int mode = (world_readable ? 0755 : 0700);
     char *subdir;
     unsigned int i;
 
@@ -211,10 +211,11 @@ tempfilename (const void *ctx)
  * is not touched).
  */
 static int
-maildir_mktemp (const void *ctx, const char *maildir, char **path_out)
+maildir_mktemp (const void *ctx, const char *maildir, bool world_readable, char **path_out)
 {
     char *filename, *path;
     int fd;
+    const int mode = (world_readable ? 0644 : 0600);
 
     do {
 	filename = tempfilename (ctx);
@@ -227,7 +228,7 @@ maildir_mktemp (const void *ctx, const char *maildir, char **path_out)
 	    return -1;
 	}
 
-	fd = open (path, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 0600);
+	fd = open (path, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, mode);
     } while (fd == -1 && errno == EEXIST);
 
     if (fd == -1) {
@@ -289,12 +290,12 @@ copy_fd (int fdout, int fdin)
  * the file, or NULL on errors.
  */
 static char *
-maildir_write_tmp (const void *ctx, int fdin, const char *maildir)
+maildir_write_tmp (const void *ctx, int fdin, const char *maildir, bool world_readable)
 {
     char *path;
     int fdout;
 
-    fdout = maildir_mktemp (ctx, maildir, &path);
+    fdout = maildir_mktemp (ctx, maildir, world_readable, &path);
     if (fdout < 0)
 	return NULL;
 
@@ -323,11 +324,11 @@ FAIL:
  * errors.
  */
 static char *
-maildir_write_new (const void *ctx, int fdin, const char *maildir)
+maildir_write_new (const void *ctx, int fdin, const char *maildir, bool world_readable)
 {
     char *cleanpath, *tmppath, *newpath, *newdir;
 
-    tmppath = maildir_write_tmp (ctx, fdin, maildir);
+    tmppath = maildir_write_tmp (ctx, fdin, maildir, world_readable);
     if (! tmppath)
 	return NULL;
     cleanpath = tmppath;
@@ -457,6 +458,7 @@ notmuch_insert_command (notmuch_config_t *config, int argc, char *argv[])
     bool create_folder = false;
     bool keep = false;
     bool hooks = true;
+    bool world_readable = false;
     bool synchronize_flags;
     char *maildir;
     char *newpath;
@@ -467,7 +469,8 @@ notmuch_insert_command (notmuch_config_t *config, int argc, char *argv[])
 	{ .opt_string = &folder, .name = "folder", .allow_empty = true },
 	{ .opt_bool = &create_folder, .name = "create-folder" },
 	{ .opt_bool = &keep, .name = "keep" },
-	{ .opt_bool =  &hooks, .name = "hooks" },
+	{ .opt_bool = &hooks, .name = "hooks" },
+	{ .opt_bool = &world_readable, .name = "world-readable" },
 	{ .opt_inherit = notmuch_shared_indexing_options },
 	{ .opt_inherit = notmuch_shared_options },
 	{ }
@@ -523,7 +526,7 @@ notmuch_insert_command (notmuch_config_t *config, int argc, char *argv[])
     }
 
     strip_trailing (maildir, '/');
-    if (create_folder && ! maildir_create_folder (config, maildir))
+    if (create_folder && ! maildir_create_folder (config, maildir, world_readable))
 	return EXIT_FAILURE;
 
     /* Set up our handler for SIGINT. We do not set SA_RESTART so that copying
@@ -535,7 +538,7 @@ notmuch_insert_command (notmuch_config_t *config, int argc, char *argv[])
     sigaction (SIGINT, &action, NULL);
 
     /* Write the message to the Maildir new directory. */
-    newpath = maildir_write_new (config, STDIN_FILENO, maildir);
+    newpath = maildir_write_new (config, STDIN_FILENO, maildir, world_readable);
     if (! newpath) {
 	return EXIT_FAILURE;
     }
diff --git a/test/T070-insert.sh b/test/T070-insert.sh
index 40519bb2..05be473a 100755
--- a/test/T070-insert.sh
+++ b/test/T070-insert.sh
@@ -4,6 +4,10 @@ test_description='"notmuch insert"'
 
 test_require_external_prereq gdb
 
+# subtests about file permissions assume that we're working with umask
+# 022 by default.
+umask 022
+
 # Create directories and database before inserting.
 mkdir -p "$MAIL_DIR"/{cur,new,tmp}
 mkdir -p "$MAIL_DIR"/Drafts/{cur,new,tmp}
@@ -37,6 +41,9 @@ notmuch insert < "$gen_msg_filename"
 cur_msg_filename=$(notmuch search --output=files "subject:insert-subject")
 test_expect_equal_file "$cur_msg_filename" "$gen_msg_filename"
 
+test_begin_subtest "Permissions on inserted message should be 0600"
+test_expect_equal "600" "$(stat -c %a "$cur_msg_filename")"
+
 test_begin_subtest "Insert message adds default tags"
 output=$(notmuch show --format=json "subject:insert-subject")
 expected='[[[{
@@ -73,6 +80,27 @@ notmuch insert +custom < "$gen_msg_filename"
 output=$(notmuch search --output=messages tag:custom)
 test_expect_equal "$output" "id:$gen_msg_id"
 
+test_begin_subtest "Insert tagged world-readable message"
+gen_insert_msg
+notmuch insert --world-readable +world-readable-test < "$gen_msg_filename"
+cur_msg_filename=$(notmuch search --output=files "tag:world-readable-test")
+test_expect_equal_file "$cur_msg_filename" "$gen_msg_filename"
+
+test_begin_subtest "Permissions on inserted world-readable message should be 0644"
+test_expect_equal "644" "$(stat -c %a "$cur_msg_filename")"
+
+test_begin_subtest "Insert tagged world-readable message with group-only umask"
+oldumask=$(umask)
+umask 027
+gen_insert_msg
+notmuch insert --world-readable +world-readable-umask-test < "$gen_msg_filename"
+cur_msg_filename=$(notmuch search --output=files "tag:world-readable-umask-test")
+umask "$oldumask"
+test_expect_equal_file "$cur_msg_filename" "$gen_msg_filename"
+
+test_begin_subtest "Permissions on inserted world-readable message with funny umask should be 0640"
+test_expect_equal "640" "$(stat -c %a "$cur_msg_filename")"
+
 test_begin_subtest "Insert message, add/remove tags"
 gen_insert_msg
 notmuch insert +custom -unread < "$gen_msg_filename"
@@ -170,6 +198,23 @@ output=$(notmuch search --output=files path:F/G/H/I/J/new tag:folder)
 basename=$(basename "$output")
 test_expect_equal_file "$gen_msg_filename" "${MAIL_DIR}/F/G/H/I/J/new/${basename}"
 
+test_begin_subtest "Created subfolder should have permissions 0700"
+test_expect_equal "700" "$(stat -c %a "${MAIL_DIR}/F/G/H/I/J")"
+test_begin_subtest "Created subfolder new/ should also have permissions 0700"
+test_expect_equal "700" "$(stat -c %a "${MAIL_DIR}/F/G/H/I/J/new")"
+
+test_begin_subtest "Insert message, create world-readable subfolder"
+gen_insert_msg
+notmuch insert --folder=F/G/H/I/J/K --create-folder --world-readable +folder-world-readable < "$gen_msg_filename"
+output=$(notmuch search --output=files path:F/G/H/I/J/K/new tag:folder-world-readable)
+basename=$(basename "$output")
+test_expect_equal_file "$gen_msg_filename" "${MAIL_DIR}/F/G/H/I/J/K/new/${basename}"
+
+test_begin_subtest "Created world-readable subfolder should have permissions 0755"
+test_expect_equal "755" "$(stat -c %a "${MAIL_DIR}/F/G/H/I/J/K")"
+test_begin_subtest "Created world-readable subfolder new/ should also have permissions 0755"
+test_expect_equal "755" "$(stat -c %a "${MAIL_DIR}/F/G/H/I/J/K/new")"
+
 test_begin_subtest "Insert message, create existing subfolder"
 gen_insert_msg
 notmuch insert --folder=F/G/H/I/J --create-folder +folder < "$gen_msg_filename"