Mail 5.8.0 fails to send emails when sender display name contains Cyrillic characters

[nemzorov]

Steps to reproduce

1. Upgrade Nextcloud Mail from 5.7.x to 5.8.0
2. Configure a mail account with a Cyrillic display name, for example:
   Иванов Иван Иванович ivanov@company.ru
3. Compose and send an email
4. Sending fails with:
   Horde_Mime_Exception: Address is missing domain.
5. Change the sender display name to Latin characters or to the email address itself
6. Sending works correctly

Expected behavior

Emails should be sent successfully regardless of whether the sender display name contains non-ASCII characters (UTF-8/Cyrillic).

Properly MIME-encoded From headers should be accepted and processed correctly by the Mail app and Horde transport layer.

Actual behavior

Sending fails when the sender display name contains Cyrillic characters.

Nextcloud logs:

Horde_Mime_Exception: Address is missing domain.

The generated From header is MIME-encoded correctly:

From: =?utf-8?b?0JjQstCw0L3QvtCyINCY0LLQsNC9INCY0LLQsNC90L7QstC40Yc=?= ivanov@company.ru

However, Mail/Horde appears to re-parse the already encoded header incorrectly during sending, causing the encoded display name to be interpreted as an invalid email address without a domain.

Using only Latin characters in the sender display name avoids the issue.

Mail app version

No response

Nextcloud version

No response

Mailserver or service

No response

Operating system

No response

PHP engine version

None

Nextcloud memory caching

No response

Web server

None

Database

None

Additional info

No response

[ChristophWurst]

Thanks for the report.

Could you share the full entry from nextcloud.log with the stack trace? Thanks

[nemzorov]

Horde_Mime_Exception
Address is missing domain.
/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Mail.php
Линия 479
Horde_Mime_Part->send()
/var/www/nextcloud/apps/mail/lib/Service/MailTransmission.php
Линия 158
Horde_Mime_Mail->send()
/var/www/nextcloud/apps/mail/lib/Send/SendHandler.php
Линия 32
OCA\Mail\Service\MailTransmission->sendMessage()
/var/www/nextcloud/apps/mail/lib/Send/AHandler.php
Линия 34
OCA\Mail\Send\SendHandler->process()
/var/www/nextcloud/apps/mail/lib/Send/AntiAbuseHandler.php
Линия 55
OCA\Mail\Send\AHandler->processNext()
/var/www/nextcloud/apps/mail/lib/Send/AHandler.php
Линия 34
OCA\Mail\Send\AntiAbuseHandler->process()
/var/www/nextcloud/apps/mail/lib/Send/SentMailboxHandler.php
Линия 25
OCA\Mail\Send\AHandler->processNext()
/var/www/nextcloud/apps/mail/lib/Send/Chain.php
Линия 54
OCA\Mail\Send\SentMailboxHandler->process()
/var/www/nextcloud/apps/mail/lib/Service/OutboxService.php
Линия 123
OCA\Mail\Send\Chain->process()
/var/www/nextcloud/apps/mail/lib/Controller/OutboxController.php
Линия 245
OCA\Mail\Service\OutboxService->sendMessage()
/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php
Линия 205
OCA\Mail\Controller\OutboxController->send()
/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php
Линия 118
OC\AppFramework\Http\Dispatcher->executeController()
/var/www/nextcloud/lib/private/AppFramework/App.php
Линия 153
OC\AppFramework\Http\Dispatcher->dispatch()
/var/www/nextcloud/lib/private/Route/Router.php
Линия 321
OC\AppFramework\App::main()
/var/www/nextcloud/lib/base.php
Линия 1155
OC\Route\Router->match()
/var/www/nextcloud/index.php
Линия 25
OC::handleRequest()
Вызвано Horde_Mail_Exception
Address is missing domain.

{
  "reqId": "*****",
  "level": 3,
  "time": "2026-05-21T10:18:23+00:00",
  "remoteAddr": "***.***.**.**",
  "user": "ivanov@company.ru",
  "app": "mail",
  "method": "POST",
  "url": "/index.php/apps/mail/api/outbox/XXX",
  "scriptName": "/index.php",
  "message": "Address is missing domain.",
  "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/148.0.0.0 Safari/537.36",
  "version": "33.0.3.2",
  "exception": {
    "Exception": "Horde_Mime_Exception",
    "Message": "Address is missing domain.",
    "Code": 0,
    "Trace": [
      {
        "file": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Mail.php",
        "line": 479,
        "function": "send",
        "class": "Horde_Mime_Part",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/mail/lib/Service/MailTransmission.php",
        "line": 158,
        "function": "send",
        "class": "Horde_Mime_Mail",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/mail/lib/Send/SendHandler.php",
        "line": 32,
        "function": "sendMessage",
        "class": "OCA\\Mail\\Service\\MailTransmission",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/mail/lib/Send/AHandler.php",
        "line": 34,
        "function": "process",
        "class": "OCA\\Mail\\Send\\SendHandler",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/mail/lib/Send/AntiAbuseHandler.php",
        "line": 55,
        "function": "processNext",
        "class": "OCA\\Mail\\Send\\AHandler",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/mail/lib/Send/AHandler.php",
        "line": 34,
        "function": "process",
        "class": "OCA\\Mail\\Send\\AntiAbuseHandler",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/mail/lib/Send/SentMailboxHandler.php",
        "line": 25,
        "function": "processNext",
        "class": "OCA\\Mail\\Send\\AHandler",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/mail/lib/Send/Chain.php",
        "line": 54,
        "function": "process",
        "class": "OCA\\Mail\\Send\\SentMailboxHandler",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/mail/lib/Service/OutboxService.php",
        "line": 123,
        "function": "process",
        "class": "OCA\\Mail\\Send\\Chain",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/apps/mail/lib/Controller/OutboxController.php",
        "line": 245,
        "function": "sendMessage",
        "class": "OCA\\Mail\\Service\\OutboxService",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",
        "line": 205,
        "function": "send",
        "class": "OCA\\Mail\\Controller\\OutboxController",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",
        "line": 118,
        "function": "executeController",
        "class": "OC\\AppFramework\\Http\\Dispatcher",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/lib/private/AppFramework/App.php",
        "line": 153,
        "function": "dispatch",
        "class": "OC\\AppFramework\\Http\\Dispatcher",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/lib/private/Route/Router.php",
        "line": 321,
        "function": "main",
        "class": "OC\\AppFramework\\App",
        "type": "::"
      },
      {
        "file": "/var/www/nextcloud/lib/base.php",
        "line": 1155,
        "function": "match",
        "class": "OC\\Route\\Router",
        "type": "->"
      },
      {
        "file": "/var/www/nextcloud/index.php",
        "line": 25,
        "function": "handleRequest",
        "class": "OC",
        "type": "::"
      }
    ],
    "File": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Part.php",
    "Line": 1642,
    "Previous": {
      "Exception": "Horde_Mail_Exception",
      "Message": "Address is missing domain.",
      "Code": 0,
      "Trace": [
        {
          "file": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Rfc822.php",
          "line": 366,
          "function": "_parseAddrSpec",
          "class": "Horde_Mail_Rfc822",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Rfc822.php",
          "line": 296,
          "function": "_parseMailbox",
          "class": "Horde_Mail_Rfc822",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Rfc822.php",
          "line": 262,
          "function": "_parseAddress",
          "class": "Horde_Mail_Rfc822",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Rfc822.php",
          "line": 182,
          "function": "_parseAddressList",
          "class": "Horde_Mail_Rfc822",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Transport.php",
          "line": 136,
          "function": "parseAddressList",
          "class": "Horde_Mail_Rfc822",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Transport/Smtphorde.php",
          "line": 133,
          "function": "prepareHeaders",
          "class": "Horde_Mail_Transport",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Part.php",
          "line": 1620,
          "function": "send",
          "class": "Horde_Mail_Transport_Smtphorde",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Mail.php",
          "line": 479,
          "function": "send",
          "class": "Horde_Mime_Part",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/lib/Service/MailTransmission.php",
          "line": 158,
          "function": "send",
          "class": "Horde_Mime_Mail",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/lib/Send/SendHandler.php",
          "line": 32,
          "function": "sendMessage",
          "class": "OCA\\Mail\\Service\\MailTransmission",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/lib/Send/AHandler.php",
          "line": 34,
          "function": "process",
          "class": "OCA\\Mail\\Send\\SendHandler",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/lib/Send/AntiAbuseHandler.php",
          "line": 55,
          "function": "processNext",
          "class": "OCA\\Mail\\Send\\AHandler",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/lib/Send/AHandler.php",
          "line": 34,
          "function": "process",
          "class": "OCA\\Mail\\Send\\AntiAbuseHandler",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/lib/Send/SentMailboxHandler.php",
          "line": 25,
          "function": "processNext",
          "class": "OCA\\Mail\\Send\\AHandler",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/lib/Send/Chain.php",
          "line": 54,
          "function": "process",
          "class": "OCA\\Mail\\Send\\SentMailboxHandler",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/lib/Service/OutboxService.php",
          "line": 123,
          "function": "process",
          "class": "OCA\\Mail\\Send\\Chain",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/apps/mail/lib/Controller/OutboxController.php",
          "line": 245,
          "function": "sendMessage",
          "class": "OCA\\Mail\\Service\\OutboxService",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",
          "line": 205,
          "function": "send",
          "class": "OCA\\Mail\\Controller\\OutboxController",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",
          "line": 118,
          "function": "executeController",
          "class": "OC\\AppFramework\\Http\\Dispatcher",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/lib/private/AppFramework/App.php",
          "line": 153,
          "function": "dispatch",
          "class": "OC\\AppFramework\\Http\\Dispatcher",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/lib/private/Route/Router.php",
          "line": 321,
          "function": "main",
          "class": "OC\\AppFramework\\App",
          "type": "::"
        },
        {
          "file": "/var/www/nextcloud/lib/base.php",
          "line": 1155,
          "function": "match",
          "class": "OC\\Route\\Router",
          "type": "->"
        },
        {
          "file": "/var/www/nextcloud/index.php",
          "line": 25,
          "function": "handleRequest",
          "class": "OC",
          "type": "::"
        }
      ],
      "File": "/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Rfc822.php",
      "Line": 423
    },
    "message": "Address is missing domain.",
    "exception": "{\"class\":\"Horde_Mime_Exception\",\"message\":\"Address is missing domain.\",\"code\":0,\"file\":\"/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Part.php:1642\",\"trace\":\"#0 /var/www/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Mail.php(479): Horde_Mime_Part->send()\\n#1 /var/www/nextcloud/apps/mail/lib/Service/MailTransmission.php(158): Horde_Mime_Mail->send()\\n#2 /var/www/nextcloud/apps/mail/lib/Send/SendHandler.php(32): OCA\\Mail\\Service\\MailTransmission->sendMessage()\\n#3 /var/www/nextcloud/apps/mail/lib/Send/AHandler.php(34): OCA\\Mail\\Send\\SendHandler->process()\\n#4 /var/www/nextcloud/apps/mail/lib/Send/AntiAbuseHandler.php(55): OCA\\Mail\\Send\\AHandler->processNext()\\n#5 /var/www/nextcloud/apps/mail/lib/Send/AHandler.php(34): OCA\\Mail\\Send\\AntiAbuseHandler->process()\\n#6 /var/www/nextcloud/apps/mail/lib/Send/SentMailboxHandler.php(25): OCA\\Mail\\Send\\AHandler->processNext()\\n#7 /var/www/nextcloud/apps/mail/lib/Send/Chain.php(54): OCA\\Mail\\Send\\SentMailboxHandler->process()\\n#8 /var/www/nextcloud/apps/mail/lib/Service/OutboxService.php(123): OCA\\Mail\\Send\\Chain->process()\\n#9 /var/www/nextcloud/apps/mail/lib/Controller/OutboxController.php(245): OCA\\Mail\\Service\\OutboxService->sendMessage()\\n#10 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(205): OCA\\Mail\\Controller\\OutboxController->send()\\n#11 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(118): OC\\AppFramework\\Http\\Dispatcher->executeController()\\n#12 /var/www/nextcloud/lib/private/AppFramework/App.php(153): OC\\AppFramework\\Http\\Dispatcher->dispatch()\\n#13 /var/www/nextcloud/lib/private/Route/Router.php(321): OC\\AppFramework\\App::main()\\n#14 /var/www/nextcloud/lib/base.php(1155): OC\\Route\\Router->match()\\n#15 /var/www/nextcloud/index.php(25): OC::handleRequest()\\n#16 {main}\",\"previous\":{\"class\":\"Horde_Mail_Exception\",\"message\":\"Address is missing domain.\",\"code\":0,\"file\":\"/var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Rfc822.php:423\",\"trace\":\"#0 /var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Rfc822.php(366): Horde_Mail_Rfc822->_parseAddrSpec()\\n#1 /var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Rfc822.php(296): Horde_Mail_Rfc822->_parseMailbox()\\n#2 /var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Rfc822.php(262): Horde_Mail_Rfc822->_parseAddress()\\n#3 /var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Rfc822.php(182): Horde_Mail_Rfc822->_parseAddressList()\\n#4 /var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Transport.php(136): Horde_Mail_Rfc822->parseAddressList()\\n#5 /var/www/nextcloud/apps/mail/vendor/bytestream/horde-mail/lib/Horde/Mail/Transport/Smtphorde.php(133): Horde_Mail_Transport->prepareHeaders()\\n#6 /var/www/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Part.php(1620): Horde_Mail_Transport_Smtphorde->send()\\n#7 /var/www/nextcloud/apps/mail/vendor/bytestream/horde-mime/lib/Horde/Mime/Mail.php(479): Horde_Mime_Part->send()\\n#8 /var/www/nextcloud/apps/mail/lib/Service/MailTransmission.php(158): Horde_Mime_Mail->send()\\n#9 /var/www/nextcloud/apps/mail/lib/Send/SendHandler.php(32): OCA\\Mail\\Service\\MailTransmission->sendMessage()\\n#10 /var/www/nextcloud/apps/mail/lib/Send/AHandler.php(34): OCA\\Mail\\Send\\SendHandler->process()\\n#11 /var/www/nextcloud/apps/mail/lib/Send/AntiAbuseHandler.php(55): OCA\\Mail\\Send\\AHandler->processNext()\\n#12 /var/www/nextcloud/apps/mail/lib/Send/AHandler.php(34): OCA\\Mail\\Send\\AntiAbuseHandler->process()\\n#13 /var/www/nextcloud/apps/mail/lib/Send/SentMailboxHandler.php(25): OCA\\Mail\\Send\\AHandler->processNext()\\n#14 /var/www/nextcloud/apps/mail/lib/Send/Chain.php(54): OCA\\Mail\\Send\\SentMailboxHandler->process()\\n#15 /var/www/nextcloud/apps/mail/lib/Service/OutboxService.php(123): OCA\\Mail\\Send\\Chain->process()\\n#16 /var/www/nextcloud/apps/mail/lib/Controller/OutboxController.php(245): OCA\\Mail\\Service\\OutboxService->sendMessage()\\n#17 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(205): OCA\\Mail\\Controller\\OutboxController->send()\\n#18 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(118): OC\\AppFramework\\Http\\Dispatcher->executeController()\\n#19 /var/www/nextcloud/lib/private/AppFramework/App.php(153): OC\\AppFramework\\Http\\Dispatcher->dispatch()\\n#20 /var/www/nextcloud/lib/private/Route/Router.php(321): OC\\AppFramework\\App::main()\\n#21 /var/www/nextcloud/lib/base.php(1155): OC\\Route\\Router->match()\\n#22 /var/www/nextcloud/index.php(25): OC::handleRequest()\\n#23 {main}\"}}",
    "CustomMessage": "Address is missing domain."
  },
  "id": "***"
}