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Getting help
In order to help you as efficiently (and quickly!) as possible, please fill in as much of the below requested information as you can.
Before clicking submit: Please check if your query is already addressed via the following resources:
- Official documentation (searchable and regularly updated)
- How to topics and FAQs
- Forum search
(Utilizing these existing resources is typically faster. It also helps reduce the load on our generous volunteers while elevating the signal to noise ratio of the forums otherwise arising from the same queries being posted repeatedly).
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can. 
The Basics
- Nextcloud Server version (e.g., 29.x.x):
33.0.3 (Winter 2026)
- Operating system and version (e.g., Ubuntu 24.04):
Ubuntu 24.04.4 LTS
- Web server and version (e.g, Apache 2.4.25):
Apache 2.4.6 (via AIO containers)
- Reverse proxy and version _(e.g. nginx 1.27.2)
Docker AIO setup
- PHP version (e.g, 8.3):
8.3.0
- Is this the first time you’ve seen this error? (Yes / No):
no
- When did this problem seem to first start?
On a fresh NextCloud AIO installation
- Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
NextCloud AIO
- Are you using CloudfIare, mod_security, or similar? (Yes / No)
no
Summary of the issue you are facing:
Whenever I go to send the test e-mail to validate my configuration, no matter what e-mail server I use (whether it’s my private server or SendGrid’s public relay), I get the error that says to check the mail server log and that the email could not be sent.
Steps to replicate it (hint: details matter!):
- Open Admin Settings, then Basic Settings and scroll down to the e-mail server section.
- Fill in your server details. I am trying to use STARTTLS on port 587 on both servers I’ve tried. The servers require authentication.
- Click Send Test E-mail.
Log entries
Nextcloud
Please provide the log entries from your Nextcloud log that are generated during the time of problem (via the Copy raw option from Administration settings->Logging screen or from your nextcloud.log located in your data directory). Feel free to use a pastebin/gist service if necessary.
{"reqId":"Gu9RutCoqMwu7t6nD7DZ","level":3,"time":"2026-04-30T23:30:45+00:00","remoteAddr":"136.32.104.196","user":"admin","app":"settings","method":"POST","url":"/settings/admin/mailtest","scriptName":"/index.php","message":"Failed sending test email: Email could not be sent. Check your mail server log","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:150.0) Gecko/20100101 Firefox/150.0","version":"33.0.3.2","exception":{"Exception":"RuntimeException","Message":"Email could not be sent. Check your mail server log","Code":0,"Trace":[{"file":"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php","line":205,"function":"sendTestMail","class":"OCA\\Settings\\Controller\\MailSettingsController","type":"->","args":[]},{"file":"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php","line":118,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OCA\\Settings\\Controller\\MailSettingsController"},"sendTestMail"]},{"file":"/var/www/html/lib/private/AppFramework/App.php","line":153,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OCA\\Settings\\Controller\\MailSettingsController"},"sendTestMail"]},{"file":"/var/www/html/lib/private/Route/Router.php","line":321,"function":"main","class":"OC\\AppFramework\\App","type":"::","args":["OCA\\Settings\\Controller\\MailSettingsController","sendTestMail",{"__class__":"OC\\AppFramework\\DependencyInjection\\DIContainer"},{"_route":"settings.mailsettings.sendtestmail"}]},{"file":"/var/www/html/lib/base.php","line":1155,"function":"match","class":"OC\\Route\\Router","type":"->","args":["/settings/admin/mailtest"]},{"file":"/var/www/html/index.php","line":25,"function":"handleRequest","class":"OC","type":"::","args":[]}],"File":"/var/www/html/apps/settings/lib/Controller/MailSettingsController.php","Line":148,"message":"Failed sending test email: Email could not be sent. Check your mail server log","exception":"{\"class\":\"RuntimeException\",\"message\":\"Email could not be sent. Check your mail server log\",\"code\":0,\"file\":\"/var/www/html/apps/settings/lib/Controller/MailSettingsController.php:148\",\"trace\":\"#0 /var/www/html/lib/private/AppFramework/Http/Dispatcher.php(205): OCA\\Settings\\Controller\\MailSettingsController->sendTestMail()\\n#1 /var/www/html/lib/private/AppFramework/Http/Dispatcher.php(118): OC\\AppFramework\\Http\\Dispatcher->executeController(Object(OCA\\Settings\\Controller\\MailSettingsController), 'sendTestMail')\\n#2 /var/www/html/lib/private/AppFramework/App.php(153): OC\\AppFramework\\Http\\Dispatcher->dispatch(Object(OCA\\Settings\\Controller\\MailSettingsController), 'sendTestMail')\\n#3 /var/www/html/lib/private/Route/Router.php(321): OC\\AppFramework\\App::main('OCA\\\\Settings\\\\Co...', 'sendTestMail', Object(OC\\AppFramework\\DependencyInjection\\DIContainer), Array)\\n#4 /var/www/html/lib/base.php(1155): OC\\Route\\Router->match('/settings/admin...')\\n#5 /var/www/html/index.php(25): OC::handleRequest()\\n#6 {main}\"}","CustomMessage":"Failed sending test email: Email could not be sent. Check your mail server log"},"id":"69f3e661e0343"}
Web Browser
If the problem is related to the Web interface, open your browser inspector Console and Network tabs while refreshing (reloading) and reproducing the problem. Provide any relevant output/errors here that appear.
Not applicable
Web server / Reverse Proxy
The output of your Apache/nginx/system log in /var/log/____:
Not applicable
Configuration
Nextcloud
The output of occ config:list system or similar is best, but, if not possible, the contents of your config.php file from /path/to/nextcloud is fine (make sure to remove any identifiable information!):
docker exec --user www-data nextcloud-aio-nextcloud php occ config:list system
{
"system": {
"one-click-instance": true,
"one-click-instance.user-limit": 100,
"memcache.local": "\\OC\\Memcache\\APCu",
"apps_paths": [
{
"path": "\/var\/www\/html\/apps",
"url": "\/apps",
"writable": false
},
{
"path": "\/var\/www\/html\/custom_apps",
"url": "\/custom_apps",
"writable": true
}
],
"check_data_directory_permissions": false,
"memcache.distributed": "\\OC\\Memcache\\Redis",
"memcache.locking": "\\OC\\Memcache\\Redis",
"redis": {
"host": "***REMOVED SENSITIVE VALUE***",
"password": "***REMOVED SENSITIVE VALUE***",
"port": 6379
},
"overwritehost": "files.district12.xyz",
"overwriteprotocol": "https",
"passwordsalt": "***REMOVED SENSITIVE VALUE***",
"secret": "***REMOVED SENSITIVE VALUE***",
"trusted_domains": [
"localhost",
"files.district12.xyz"
],
"datadirectory": "***REMOVED SENSITIVE VALUE***",
"dbtype": "pgsql",
"version": "33.0.3.2",
"overwrite.cli.url": "https:\/\/files.district12.xyz\/",
"dbname": "***REMOVED SENSITIVE VALUE***",
"dbhost": "***REMOVED SENSITIVE VALUE***",
"dbtableprefix": "oc_",
"dbuser": "***REMOVED SENSITIVE VALUE***",
"dbpassword": "***REMOVED SENSITIVE VALUE***",
"installed": true,
"instanceid": "***REMOVED SENSITIVE VALUE***",
"maintenance": false,
"updatechecker": true,
"updatedirectory": "\/nc-updater",
"loglevel": 3,
"app_install_overwrite": [
"nextcloud-aio"
],
"log_type": "file",
"logfile": "\/var\/www\/html\/data\/nextcloud.log",
"log_rotate_size": 10485760,
"log.condition": {
"apps": [
"admin_audit"
]
},
"preview_max_x": 2048,
"preview_max_y": 2048,
"jpeg_quality": 60,
"enabledPreviewProviders": {
"1": "OC\\Preview\\Image",
"2": "OC\\Preview\\MarkDown",
"3": "OC\\Preview\\MP3",
"4": "OC\\Preview\\TXT",
"5": "OC\\Preview\\OpenDocument",
"6": "OC\\Preview\\Movie",
"7": "OC\\Preview\\Krita",
"0": "OC\\Preview\\Imaginary",
"23": "OC\\Preview\\ImaginaryPDF"
},
"enable_previews": true,
"upgrade.disable-web": true,
"mail_smtpmode": "smtp",
"trashbin_retention_obligation": "auto, 30",
"versions_retention_obligation": "auto, 30",
"activity_expire_days": 30,
"simpleSignUpLink.shown": false,
"share_folder": "\/Shared",
"one-click-instance.link": "https:\/\/nextcloud.com\/all-in-one\/",
"upgrade.cli-upgrade-link": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/2726",
"maintenance_window_start": 100,
"allow_local_remote_servers": true,
"davstorage.request_timeout": 3600,
"documentation_url.server_logs": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/5425",
"htaccess.RewriteBase": "\/",
"dbpersistent": false,
"auth.bruteforce.protection.enabled": true,
"ratelimit.protection.enabled": true,
"files_external_allow_create_new_local": false,
"trusted_proxies": "***REMOVED SENSITIVE VALUE***",
"preview_imaginary_url": "***REMOVED SENSITIVE VALUE***",
"preview_imaginary_key": "***REMOVED SENSITIVE VALUE***",
"default_phone_region": "us",
"config_preset": 2,
"DOMAIN": "files.district12.xyz",
"AIO_VERSION": "v12.9.2"
}
}
Apps
The output of occ app:list (if possible).
docker exec --user www-data nextcloud-aio-nextcloud php occ app:list
Enabled:
- activity: 6.0.0
- admin_audit: 1.23.0
- app_api: 33.0.0
- bruteforcesettings: 6.0.0
- calendar: 6.2.3
- circles: 33.0.0
- cloud_federation_api: 1.17.0
- comments: 1.23.0
- contacts: 8.4.5
- contactsinteraction: 1.14.1
- dashboard: 7.13.0
- dav: 1.36.0
- deck: 1.17.1
- encryption: 2.21.0
- federatedfilesharing: 1.23.0
- federation: 1.23.0
- files: 2.5.0
- files_antivirus: 6.2.0
- files_downloadlimit: 5.1.0
- files_external: 1.25.1
- files_fulltextsearch: 33.0.0
- files_pdfviewer: 6.0.0
- files_reminders: 1.6.0
- files_sharing: 1.25.2
- files_trashbin: 1.23.0
- files_versions: 1.26.0
- firstrunwizard: 6.0.0
- fulltextsearch: 33.0.0
- fulltextsearch_elasticsearch: 33.0.0
- guests: 4.7.0
- logreader: 6.0.0
- lookup_server_connector: 1.21.0
- nextcloud-aio: 0.8.0
- nextcloud_announcements: 5.0.0
- notes: 5.0.0
- notifications: 6.0.0
- notify_push: 1.3.1
- oauth2: 1.21.0
- password_policy: 5.0.0
- photos: 6.0.0
- privacy: 5.0.0
- profile: 1.2.0
- provisioning_api: 1.23.0
- recommendations: 6.0.0
- related_resources: 4.0.0
- richdocuments: 10.1.2
- serverinfo: 5.0.0
- settings: 1.16.0
- sharebymail: 1.23.0
- spreed: 23.0.4
- support: 5.0.0
- survey_client: 5.0.0
- systemtags: 1.23.0
- tasks: 0.17.1
- text: 7.0.1
- theming: 2.8.0
- twofactor_backupcodes: 1.22.0
- twofactor_totp: 15.0.0
- twofactor_webauthn: 2.6.0
- updatenotification: 1.23.0
- user_status: 1.13.0
- viewer: 6.0.0
- weather_status: 1.13.0
- webhook_listeners: 1.5.0
- whiteboard: 1.5.7
- workflowengine: 2.15.0
Disabled:
- suspicious_login: 11.0.0
- testing: 1.23.0
- twofactor_nextcloud_notification: 7.0.0
- user_ldap: 1.24.0
It is also important to note that I get a second error mentioning the inability to connect to 127.0.0.1:25 at the time I try to send the test e-mail, and I’m not even using sendmail. See below:
{"reqId":"n3iIcHvPA0PCw7HtI8t9","level":3,"time":"2026-04-30T23:46:40+00:00","remoteAddr":"136.32.104.196","user":"admin","app":"core","method":"POST","url":"/settings/admin/mailtest","scriptName":"/index.php","message":"Sending mail to \"Array\n(\n [tyler@district12.xyz] => Tyler Kavanaugh\n)\n\" with subject \"Email setting test\" failed","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:150.0) Gecko/20100101 Firefox/150.0","version":"33.0.3.2","exception":{"Exception":"Symfony\\Component\\Mailer\\Exception\\TransportException","Message":"Connection could not be established with host \"127.0.0.1:25\": stream_socket_client(): Unable to connect to 127.0.0.1:25 (Connection refused)","Code":0,"Trace":[{"function":"Symfony\\Component\\Mailer\\Transport\\Smtp\\Stream\\{closure}","class":"Symfony\\Component\\Mailer\\Transport\\Smtp\\Stream\\SocketStream","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/html/3rdparty/symfony/mailer/Transport/Smtp/Stream/SocketStream.php","line":157,"function":"stream_socket_client","args":["127.0.0.1:25",0,"",10,4,null]},{"file":"/var/www/html/3rdparty/symfony/mailer/Transport/Smtp/SmtpTransport.php","line":264,"function":"initialize","class":"Symfony\\Component\\Mailer\\Transport\\Smtp\\Stream\\SocketStream","type":"->","args":[]},{"file":"/var/www/html/3rdparty/symfony/mailer/Transport/Smtp/SmtpTransport.php","line":199,"function":"start","class":"Symfony\\Component\\Mailer\\Transport\\Smtp\\SmtpTransport","type":"->","args":[]},{"file":"/var/www/html/3rdparty/symfony/mailer/Transport/AbstractTransport.php","line":69,"function":"doSend","class":"Symfony\\Component\\Mailer\\Transport\\Smtp\\SmtpTransport","type":"->","args":[{"__class__":"Symfony\\Component\\Mailer\\SentMessage"}]},{"file":"/var/www/html/3rdparty/symfony/mailer/Transport/Smtp/SmtpTransport.php","line":137,"function":"send","class":"Symfony\\Component\\Mailer\\Transport\\AbstractTransport","type":"->","args":[{"__class__":"Symfony\\Component\\Mime\\Email"},{"__class__":"Symfony\\Component\\Mailer\\DelayedEnvelope"}]},{"file":"/var/www/html/3rdparty/symfony/mailer/Mailer.php","line":42,"function":"send","class":"Symfony\\Component\\Mailer\\Transport\\Smtp\\SmtpTransport","type":"->","args":[{"__class__":"Symfony\\Component\\Mime\\Email"},null]},{"file":"/var/www/html/lib/private/Mail/Mailer.php","line":205,"function":"send","class":"Symfony\\Component\\Mailer\\Mailer","type":"->","args":[{"__class__":"Symfony\\Component\\Mime\\Email"}]},{"file":"/var/www/html/apps/settings/lib/Controller/MailSettingsController.php","line":145,"function":"send","class":"OC\\Mail\\Mailer","type":"->","args":[{"__class__":"OC\\Mail\\Message"}]},{"file":"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php","line":205,"function":"sendTestMail","class":"OCA\\Settings\\Controller\\MailSettingsController","type":"->","args":[]},{"file":"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php","line":118,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OCA\\Settings\\Controller\\MailSettingsController"},"sendTestMail"]},{"file":"/var/www/html/lib/private/AppFramework/App.php","line":153,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OCA\\Settings\\Controller\\MailSettingsController"},"sendTestMail"]},{"file":"/var/www/html/lib/private/Route/Router.php","line":321,"function":"main","class":"OC\\AppFramework\\App","type":"::","args":["OCA\\Settings\\Controller\\MailSettingsController","sendTestMail",{"__class__":"OC\\AppFramework\\DependencyInjection\\DIContainer"},{"_route":"settings.mailsettings.sendtestmail"}]},{"file":"/var/www/html/lib/base.php","line":1155,"function":"match","class":"OC\\Route\\Router","type":"->","args":["/settings/admin/mailtest"]},{"file":"/var/www/html/index.php","line":25,"function":"handleRequest","class":"OC","type":"::","args":[]}],"File":"/var/www/html/3rdparty/symfony/mailer/Transport/Smtp/Stream/SocketStream.php","Line":154,"message":"Sending mail to \"Array\n(\n [tyler@district12.xyz] => Tyler Kavanaugh\n)\n\" with subject \"Email setting test\" failed","exception":"{\"class\":\"Symfony\\Component\\Mailer\\Exception\\TransportException\",\"message\":\"Connection could not be established with host \\\"127.0.0.1:25\\\": stream_socket_client(): Unable to connect to 127.0.0.1:25 (Connection refused)\",\"code\":0,\"file\":\"/var/www/html/3rdparty/symfony/mailer/Transport/Smtp/Stream/SocketStream.php:154\",\"trace\":\"#0 [internal function]: Symfony\\Component\\Mailer\\Transport\\Smtp\\Stream\\SocketStream->Symfony\\Component\\Mailer\\Transport\\Smtp\\Stream\\{closure}(2, 'stream_socket_c...', '/var/www/html/3...', 157)\\n#1 /var/www/html/3rdparty/symfony/mailer/Transport/Smtp/Stream/SocketStream.php(157): stream_socket_client('127.0.0.1:25', 0, '', 10.0, 4, Resource id #26)\\n#2 /var/www/html/3rdparty/symfony/mailer/Transport/Smtp/SmtpTransport.php(264): Symfony\\Component\\Mailer\\Transport\\Smtp\\Stream\\SocketStream->initialize()\\n#3 /var/www/html/3rdparty/symfony/mailer/Transport/Smtp/SmtpTransport.php(199): Symfony\\Component\\Mailer\\Transport\\Smtp\\SmtpTransport->start()\\n#4 /var/www/html/3rdparty/symfony/mailer/Transport/AbstractTransport.php(69): Symfony\\Component\\Mailer\\Transport\\Smtp\\SmtpTransport->doSend(Object(Symfony\\Component\\Mailer\\SentMessage))\\n#5 /var/www/html/3rdparty/symfony/mailer/Transport/Smtp/SmtpTransport.php(137): Symfony\\Component\\Mailer\\Transport\\AbstractTransport->send(Object(Symfony\\Component\\Mime\\Email), Object(Symfony\\Component\\Mailer\\DelayedEnvelope))\\n#6 /var/www/html/3rdparty/symfony/mailer/Mailer.php(42): Symfony\\Component\\Mailer\\Transport\\Smtp\\SmtpTransport->send(Object(Symfony\\Component\\Mime\\Email), NULL)\\n#7 /var/www/html/lib/private/Mail/Mailer.php(205): Symfony\\Component\\Mailer\\Mailer->send(Object(Symfony\\Component\\Mime\\Email))\\n#8 /var/www/html/apps/settings/lib/Controller/MailSettingsController.php(145): OC\\Mail\\Mailer->send(Object(OC\\Mail\\Message))\\n#9 /var/www/html/lib/private/AppFramework/Http/Dispatcher.php(205): OCA\\Settings\\Controller\\MailSettingsController->sendTestMail()\\n#10 /var/www/html/lib/private/AppFramework/Http/Dispatcher.php(118): OC\\AppFramework\\Http\\Dispatcher->executeController(Object(OCA\\Settings\\Controller\\MailSettingsController), 'sendTestMail')\\n#11 /var/www/html/lib/private/AppFramework/App.php(153): OC\\AppFramework\\Http\\Dispatcher->dispatch(Object(OCA\\Settings\\Controller\\MailSettingsController), 'sendTestMail')\\n#12 /var/www/html/lib/private/Route/Router.php(321): OC\\AppFramework\\App::main('OCA\\\\Settings\\\\Co...', 'sendTestMail', Object(OC\\AppFramework\\DependencyInjection\\DIContainer), Array)\\n#13 /var/www/html/lib/base.php(1155): OC\\Route\\Router->match('/settings/admin...')\\n#14 /var/www/html/index.php(25): OC::handleRequest()\\n#15 {main}\"}","CustomMessage":"Sending mail to \"Array\n(\n [tyler@district12.xyz] => Tyler Kavanaugh\n)\n\" with subject \"Email setting test\" failed"},"id":"69f3e9e6de561"}