IMAP Sync failed: The mail server has denied the request.
Open
@ChristophWurst is already working on this.
Since May 19, 2026.
0. to triage
bug
regression
- Dominant language
- JavaScript
- Stars
- 1k
- Forks
- 348
- Avg merge
- 12h 28m
- Merged PRs (30d)
- 91
Description
Steps to reproduce
- Regular operation
- Open Mail App
- Check for new mails
Expected behavior
New mails should be visible in the inbox
Actual behavior
One of multiple mailboxes doesn't sync anymore:
"CustomMessage": "Sync failed for 8:INBOX: The mail server has denied the request."
Deleting and recreating the mailbox allows for a one-time synchronization. Afterward, the error reappears, and the mailbox stops synchronizing.
Mail app version
5.7.15
Nextcloud version
AIO 32.0.8
Mailserver or service
Strato IMAP
Operating system
Ubuntu 24.04.4 LTS
PHP engine version
PHP 8.3
Nextcloud memory caching
No response
Web server
Apache (supported)
Database
PostgreSQL
Additional info
{
"reqId": "D4dn2SOficvuGSNNaVo7",
"level": 3,
"time": "2026-05-12T13:31:03+00:00",
"remoteAddr": "192.168.241.12",
"user": "schulgin",
"app": "mail",
"method": "POST",
"url": "/apps/mail/api/mailboxes/175/sync",
"scriptName": "/index.php",
"message": "Sync failed for 8:INBOX: The mail server has denied the request.",
"userAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/148.0.0.0 Safari/537.36",
"version": "32.0.8.2",
"exception": {
"Exception": "OCA\\Mail\\Exception\\ServiceException",
"Message": "Sync failed for 8:INBOX: The mail server has denied the request.",
"Code": 0,
"Trace": [
{
"file": "/var/www/html/custom_apps/mail/lib/Service/Sync/SyncService.php",
"line": 120,
"function": "sync",
"class": "OCA\\Mail\\Service\\Sync\\ImapToDbSynchronizer",
"type": "->",
"args": [
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/custom_apps/mail/lib/Controller/MailboxesController.php",
"line": 151,
"function": "syncMailbox",
"class": "OCA\\Mail\\Service\\Sync\\SyncService",
"type": "->",
"args": [
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/lib/private/AppFramework/Http/Dispatcher.php",
"line": 204,
"function": "sync",
"class": "OCA\\Mail\\Controller\\MailboxesController",
"type": "->",
"args": [
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/lib/private/AppFramework/Http/Dispatcher.php",
"line": 118,
"function": "executeController",
"class": "OC\\AppFramework\\Http\\Dispatcher",
"type": "->",
"args": [
{
"__class__": "OCA\\Mail\\Controller\\MailboxesController"
},
"sync"
]
},
{
"file": "/var/www/html/lib/private/AppFramework/App.php",
"line": 153,
"function": "dispatch",
"class": "OC\\AppFramework\\Http\\Dispatcher",
"type": "->",
"args": [
{
"__class__": "OCA\\Mail\\Controller\\MailboxesController"
},
"sync"
]
},
{
"file": "/var/www/html/lib/private/Route/Router.php",
"line": 321,
"function": "main",
"class": "OC\\AppFramework\\App",
"type": "::",
"args": [
"OCA\\Mail\\Controller\\MailboxesController",
"sync",
{
"__class__": "OC\\AppFramework\\DependencyInjection\\DIContainer"
},
{
"_route": "mail.mailboxes.sync",
"id": "175"
}
]
},
{
"file": "/var/www/html/lib/base.php",
"line": 1091,
"function": "match",
"class": "OC\\Route\\Router",
"type": "->",
"args": [
"/apps/mail/api/mailboxes/175/sync"
]
},
{
"file": "/var/www/html/index.php",
"line": 25,
"function": "handleRequest",
"class": "OC",
"type": "::",
"args": []
}
],
"File": "/var/www/html/custom_apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php",
"Line": 288,
"Previous": {
"Exception": "Horde_Imap_Client_Exception_ServerResponse",
"Message": "The mail server has denied the request.",
"Code": 20,
"Trace": [
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php",
"line": 4588,
"function": "_responseCode",
"class": "Horde_Imap_Client_Socket",
"type": "->",
"args": [
{
"__class__": "Horde_Imap_Client_Interaction_Pipeline",
"data": {
"modseqs": [],
"modseqs_nouid": [],
"esearchresp": [],
"searchresp": {
"__class__": "Horde_Imap_Client_Ids",
"duplicates": "*** sensitive parameters replaced ***"
}
},
"fetch": {
"__class__": "Horde_Imap_Client_Fetch_Results"
}
},
{
"__class__": "Horde_Imap_Client_Interaction_Server_Tagged",
"responseCode": {
"__class__": "stdClass",
"data": [],
"code": "LIMIT"
},
"status": 1,
"token": {
"__class__": "Horde_Imap_Client_Tokenize"
},
"tag": "19"
}
]
},
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php",
"line": 4321,
"function": "_getLine",
"class": "Horde_Imap_Client_Socket",
"type": "->",
"args": [
{
"__class__": "Horde_Imap_Client_Interaction_Pipeline",
"data": {
"modseqs": [],
"modseqs_nouid": [],
"esearchresp": [],
"searchresp": {
"__class__": "Horde_Imap_Client_Ids",
"duplicates": "*** sensitive parameters replaced ***"
}
},
"fetch": {
"__class__": "Horde_Imap_Client_Fetch_Results"
}
}
]
},
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php",
"line": 4245,
"function": "_sendCmdChunk",
"class": "Horde_Imap_Client_Socket",
"type": "->",
"args": [
{
"__class__": "Horde_Imap_Client_Interaction_Pipeline",
"data": {
"modseqs": [],
"modseqs_nouid": [],
"esearchresp": [],
"searchresp": {
"__class__": "Horde_Imap_Client_Ids",
"duplicates": "*** sensitive parameters replaced ***"
}
},
"fetch": {
"__class__": "Horde_Imap_Client_Fetch_Results"
}
},
[
{
"__class__": "Horde_Imap_Client_Interaction_Command",
"debug": [],
"literalplus": "*** sensitive parameters replaced ***",
"literal8": "*** sensitive parameters replaced ***",
"on_error": "*** sensitive parameters replaced ***",
"on_success": "*** sensitive parameters replaced ***",
"pipeline": {
"__class__": "Horde_Imap_Client_Interaction_Pipeline",
"data": {
"modseqs": [],
"modseqs_nouid": [],
"esearchresp": [],
"searchresp": {
"__class__": "Horde_Imap_Client_Ids",
"duplicates": "*** sensitive parameters replaced ***"
}
},
"fetch": {
"__class__": "Horde_Imap_Client_Fetch_Results"
}
},
"response": {
"__class__": "Horde_Imap_Client_Interaction_Server_Tagged",
"responseCode": {
"__class__": "stdClass",
"data": [],
"code": "LIMIT"
},
"status": 1,
"token": {
"__class__": "Horde_Imap_Client_Tokenize"
},
"tag": "19"
},
"tag": "19"
}
]
]
},
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php",
"line": 2478,
"function": "_sendCmd",
"class": "Horde_Imap_Client_Socket",
"type": "->",
"args": [
{
"__class__": "Horde_Imap_Client_Interaction_Pipeline",
"data": {
"modseqs": [],
"modseqs_nouid": [],
"esearchresp": [],
"searchresp": {
"__class__": "Horde_Imap_Client_Ids",
"duplicates": "*** sensitive parameters replaced ***"
}
},
"fetch": {
"__class__": "Horde_Imap_Client_Fetch_Results"
}
}
]
},
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Base.php",
"line": 2282,
"function": "_search",
"class": "Horde_Imap_Client_Socket",
"type": "->",
"args": [
{
"__class__": "Horde_Imap_Client_Search_Query"
},
{
"nocache": "*** sensitive parameters replaced ***",
"results": [
2,
1
],
"_query": {
"charset": "*** sensitive parameters replaced ***",
"exts": [],
"query": {
"__class__": "Horde_Imap_Client_Data_Format_List"
}
}
}
]
},
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Base.php",
"line": 2840,
"function": "search",
"class": "Horde_Imap_Client_Base",
"type": "->",
"args": [
"*** sensitive parameters replaced ***",
{
"__class__": "Horde_Imap_Client_Search_Query"
},
{
"nocache": "*** sensitive parameters replaced ***",
"results": [
2,
1
],
"_query": {
"charset": "*** sensitive parameters replaced ***",
"exts": [],
"query": {
"__class__": "Horde_Imap_Client_Data_Format_List"
}
}
}
]
},
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Base.php",
"line": 4008,
"function": "vanished",
"class": "Horde_Imap_Client_Base",
"type": "->",
"args": [
"*** sensitive parameters replaced ***",
80598,
{
"ids": {
"__class__": "Horde_Imap_Client_Ids",
"duplicates": "*** sensitive parameters replaced ***"
}
}
]
},
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Base.php",
"line": 1069,
"function": "_condstoreSync",
"class": "Horde_Imap_Client_Base",
"type": "->",
"args": []
},
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Base.php",
"line": 2247,
"function": "openMailbox",
"class": "Horde_Imap_Client_Base",
"type": "->",
"args": [
"*** sensitive parameters replaced ***",
1
]
},
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Data/Sync.php",
"line": 186,
"function": "search",
"class": "Horde_Imap_Client_Base",
"type": "->",
"args": [
"*** sensitive parameters replaced ***",
{
"__class__": "Horde_Imap_Client_Search_Query"
}
]
},
{
"file": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Base.php",
"line": 3643,
"function": "__construct",
"class": "Horde_Imap_Client_Data_Sync",
"type": "->",
"args": [
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***",
{
"U": "22075",
"V": "1549202937",
"H": "80598"
},
{
"U": 22078,
"V": 1549202937,
"H": 80610
},
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/custom_apps/mail/lib/IMAP/Sync/Synchronizer.php",
"line": 163,
"function": "sync",
"class": "Horde_Imap_Client_Base",
"type": "->",
"args": [
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/custom_apps/mail/lib/IMAP/Sync/Synchronizer.php",
"line": 135,
"function": "getNewMessageUids",
"class": "OCA\\Mail\\IMAP\\Sync\\Synchronizer",
"type": "->",
"args": [
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/custom_apps/mail/lib/IMAP/Sync/Synchronizer.php",
"line": 69,
"function": "doSplitSync",
"class": "OCA\\Mail\\IMAP\\Sync\\Synchronizer",
"type": "->",
"args": [
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/custom_apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php",
"line": 424,
"function": "sync",
"class": "OCA\\Mail\\IMAP\\Sync\\Synchronizer",
"type": "->",
"args": [
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/custom_apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php",
"line": 269,
"function": "runPartialSync",
"class": "OCA\\Mail\\Service\\Sync\\ImapToDbSynchronizer",
"type": "->",
"args": [
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***",
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/custom_apps/mail/lib/Service/Sync/SyncService.php",
"line": 120,
"function": "sync",
"class": "OCA\\Mail\\Service\\Sync\\ImapToDbSynchronizer",
"type": "->",
"args": [
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/custom_apps/mail/lib/Controller/MailboxesController.php",
"line": 151,
"function": "syncMailbox",
"class": "OCA\\Mail\\Service\\Sync\\SyncService",
"type": "->",
"args": [
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/lib/private/AppFramework/Http/Dispatcher.php",
"line": 204,
"function": "sync",
"class": "OCA\\Mail\\Controller\\MailboxesController",
"type": "->",
"args": [
"*** sensitive parameters replaced ***"
]
},
{
"file": "/var/www/html/lib/private/AppFramework/Http/Dispatcher.php",
"line": 118,
"function": "executeController",
"class": "OC\\AppFramework\\Http\\Dispatcher",
"type": "->",
"args": [
{
"__class__": "OCA\\Mail\\Controller\\MailboxesController"
},
"sync"
]
},
{
"file": "/var/www/html/lib/private/AppFramework/App.php",
"line": 153,
"function": "dispatch",
"class": "OC\\AppFramework\\Http\\Dispatcher",
"type": "->",
"args": [
{
"__class__": "OCA\\Mail\\Controller\\MailboxesController"
},
"sync"
]
},
{
"file": "/var/www/html/lib/private/Route/Router.php",
"line": 321,
"function": "main",
"class": "OC\\AppFramework\\App",
"type": "::",
"args": [
"OCA\\Mail\\Controller\\MailboxesController",
"sync",
{
"__class__": "OC\\AppFramework\\DependencyInjection\\DIContainer"
},
{
"_route": "mail.mailboxes.sync",
"id": "175"
}
]
},
{
"file": "/var/www/html/lib/base.php",
"line": 1091,
"function": "match",
"class": "OC\\Route\\Router",
"type": "->",
"args": [
"/apps/mail/api/mailboxes/175/sync"
]
},
{
"file": "/var/www/html/index.php",
"line": 25,
"function": "handleRequest",
"class": "OC",
"type": "::",
"args": []
}
],
"File": "/var/www/html/custom_apps/mail/vendor/bytestream/horde-imap-client/lib/Horde/Imap/Client/Socket.php",
"Line": 5125
},
"message": "Sync failed for 8:INBOX: The mail server has denied the request.",
"exception": [],
"CustomMessage": "Sync failed for 8:INBOX: The mail server has denied the request."
},
"id": "6a032ba3a06ba"
}
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