casa-mp-base

--- ./src/master/master-settings.c

+++ ./src/master/master-settings.c  2019-05-26 23:25:08.000000000 -0400

@@ -209,9 +209,9 @@

    .protocols = "imap pop3 lmtp",

    .listen = "*, ::",

    .ssl = "yes:no:required",

-   .default_internal_user = "dovecot",

-   .default_internal_group = "dovecot",

-   .default_login_user = "dovenull",

+   .default_internal_user = "_dovecot",

+   .default_internal_group = "_dovenull",

+   .default_login_user = "_dovenull",

    .default_process_limit = 100,

    .default_client_limit = 1000,

    .default_idle_kill = 60,

@@ -222,7 +222,10 @@

    .first_valid_uid = 500,

    .last_valid_uid = 0,

    .first_valid_gid = 1,

-   .last_valid_gid = 0,

+   /* macOS: `last_valid_gid = 100` to avoid the error */

+   /* imap: Fatal: setgroups(501) failed: Too many extra groups */

+   /* https://www.systemcodegeeks.com/mac-os/macos-dovecot-setgroups-failed/ */

+   .last_valid_gid = 100,

 #ifndef CONFIG_BINARY

    .services = ARRAY_INIT