diff --git a/services/zpush/config/imap.config.php b/services/zpush/config/imap.config.php
index d52b7b3..203e67a 100644
--- a/services/zpush/config/imap.config.php
+++ b/services/zpush/config/imap.config.php
@@ -46,3 +46,31 @@ $imap_smtp_params = array(
     'verify_peer_name' => false,
     'allow_self_signed' => true,
 );
+
+// ── Upstream defaults below — DO NOT prune. ─────────────────────────────
+// This file REPLACES the upstream template, and the backend references
+// several of these unconditionally (a missing SYSTEM_MIME_TYPES_MAPPING
+// 500'd every authenticated request on first deploy). Unused features
+// (SQL/LDAP From lookup) still need their constants defined.
+define('MAIL_MIMEPART_CRLF', "\r\n");
+define('SYSTEM_MIME_TYPES_MAPPING', '/etc/mime.types');
+define('IMAP_MEETING_USE_CALDAV', false);
+define('IMAP_SEARCH_CHARSET', 'UTF-8');
+define('IMAP_FROM_SQL_DSN', '');
+define('IMAP_FROM_SQL_USER', '');
+define('IMAP_FROM_SQL_PASSWORD', '');
+define('IMAP_FROM_SQL_OPTIONS', serialize(array(PDO::ATTR_PERSISTENT => true)));
+define('IMAP_FROM_SQL_QUERY', "select first_name, last_name, mail_address from users where mail_address = '#username@#domain'");
+define('IMAP_FROM_SQL_FIELDS', serialize(array('first_name', 'last_name', 'mail_address')));
+define('IMAP_FROM_SQL_EMAIL', '#mail_address');
+define('IMAP_FROM_SQL_FROM', '#first_name #last_name <#mail_address>');
+define('IMAP_FROM_SQL_FULLNAME', '#first_name #last_name');
+define('IMAP_FROM_LDAP_SERVER_URI', 'ldap://127.0.0.1:389/');
+define('IMAP_FROM_LDAP_USER', '');
+define('IMAP_FROM_LDAP_PASSWORD', '');
+define('IMAP_FROM_LDAP_BASE', '');
+define('IMAP_FROM_LDAP_QUERY', '(mail=#username@#domain)');
+define('IMAP_FROM_LDAP_FIELDS', serialize(array('givenname', 'sn', 'mail')));
+define('IMAP_FROM_LDAP_EMAIL', '#mail');
+define('IMAP_FROM_LDAP_FROM', '#givenname #sn <#mail>');
+define('IMAP_FROM_LDAP_FULLNAME', '#givenname #sn');