Problems with Email Send in Nextcloud 14

Steps to reproduce

I have one problem with email settings ( smtp )
When i fill the necessary fields ( all mail settings are correct ), then tryng to send test mail I get the error:

Beim Senden der E-Mail ist ein Problem aufgetreten. Bitte überprüfe Deine Einstellungen. (Fehler: Address in mailbox given [ Support@localhost.localdomain] does not comply with RFC 2822, 3.6.2.)

How can I fix this?

Expected behaviour

I can’t login in the Email Client on the Server

Actual behaviour

I have one problem with email settings ( smtp )
When i fill the necessary fields ( all mail settings are correct ), then tryng to send test mail.

Server configuration detail

Operating system: Linux 4.9.0-8-amd64 #1 SMP Debian 4.9.130-2 (2018-10-27) x86_64

Webserver: Apache/2.4.25 (Debian) (apache2handler)

Database: mysql 10.1.37

PHP version:

7.0.30-0+deb9u1
Modules loaded: Core, date, libxml, openssl, pcre, zlib, filter, hash, Reflection, SPL, session, standard, apache2handler, mysqlnd, PDO, xml, apcu, apc, bz2, calendar, ctype, curl, dom, mbstring, fileinfo, ftp, gd, gettext, iconv, intl, json, exif, mcrypt, mysqli, pdo_mysql, Phar, posix, readline, shmop, SimpleXML, sockets, sysvmsg, sysvsem, sysvshm, tokenizer, wddx, xmlreader, xmlwriter, xsl, zip, Zend OPcache

Nextcloud version: 14.0.4

Updated from an older Nextcloud/ownCloud or fresh install:

Where did you install Nextcloud from: unknown

Signing status

Array
(
)

List of activated apps
Enabled:
 - accessibility: 1.0.1
 - activity: 2.7.0
 - admin_notifications: 1.0.2
 - bookmarks_fulltextsearch: 1.0.0
 - camerarawpreviews: 0.6.1
 - cloud_federation_api: 0.0.1
 - comments: 1.4.0
 - dav: 1.6.0
 - drop_account: 0.0.13
 - federatedfilesharing: 1.4.0
 - federation: 1.4.0
 - files: 1.9.0
 - files_fulltextsearch: 1.1.1
 - files_fulltextsearch_tesseract: 1.0.0
 - files_pdfviewer: 1.3.2
 - files_rightclick: 0.8.4
 - files_sharing: 1.6.2
 - files_texteditor: 2.6.0
 - files_trashbin: 1.4.1
 - files_versions: 1.7.1
 - files_videoplayer: 1.3.0
 - firstrunwizard: 2.3.0
 - fulltextsearch: 1.1.0
 - fulltextsearch_elasticsearch: 1.0.2
 - gallery: 18.1.0
 - issuetemplate: 0.4.0
 - logreader: 2.0.0
 - lookup_server_connector: 1.2.0
 - metadata: 0.8.0
 - nextcloud_announcements: 1.3.0
 - notifications: 2.2.1
 - oauth2: 1.2.1
 - password_policy: 1.4.0
 - provisioning_api: 1.4.0
 - quicknotes: 0.1.5
 - quota_warning: 1.3.0
 - registration: 0.4.5
 - serverinfo: 1.4.0
 - sharebymail: 1.4.0
 - socialsharing_diaspora: 1.0.3
 - socialsharing_email: 1.0.4
 - socialsharing_facebook: 1.0.3
 - socialsharing_googleplus: 1.0.3
 - socialsharing_twitter: 1.0.3
 - support: 1.0.0
 - survey_client: 1.2.0
 - systemtags: 1.4.0
 - theming: 1.5.0
 - twofactor_backupcodes: 1.3.1
 - twofactor_totp: 1.5.0
 - unsplash: 1.1.1
 - updatenotification: 1.4.1
 - workflowengine: 1.4.0
Disabled:
 - admin_audit
 - encryption
 - files_external
 - user_external
 - user_ldap

Configuration (config/config.php)
{
    "instanceid": "***REMOVED SENSITIVE VALUE***",
    "passwordsalt": "***REMOVED SENSITIVE VALUE***",
    "secret": "***REMOVED SENSITIVE VALUE***",
    "trusted_domains": [
        "178.63.9.142",
        "dragon-cloud.net",
        "www.dragon-cloud.net"
    ],
    "datadirectory": "***REMOVED SENSITIVE VALUE***",
    "dbtype": "mysql",
    "version": "14.0.4.2",
    "overwrite.cli.url": "http:\/\/178.63.9.142\/nextcloud",
    "dbname": "***REMOVED SENSITIVE VALUE***",
    "dbhost": "***REMOVED SENSITIVE VALUE***",
    "dbport": "",
    "dbtableprefix": "oc_",
    "dbuser": "***REMOVED SENSITIVE VALUE***",
    "dbpassword": "***REMOVED SENSITIVE VALUE***",
    "memcache.local": "\\OC\\Memcache\\APCu",
    "installed": true,
    "mail_smtpmode": "smtp",
    "mail_smtpsecure": "ssl",
    "mail_smtpauth": 1,
    "mail_from_address": "***REMOVED SENSITIVE VALUE***",
    "mail_domain": "***REMOVED SENSITIVE VALUE***",
    "mail_smtpauthtype": "LOGIN",
    "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
    "mail_smtpport": "587",
    "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
    "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
    "maintenance": false,
    "updater.release.channel": "stable",
    "theme": "",
    "loglevel": 2
}

Are you using external storage, if yes which one: local/smb/sftp/…

Are you using encryption:

Are you using an external user-backend, if yes which one: LDAP/ActiveDirectory/Webdav/…

Client configuration

Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_1) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.0.1 Safari/605.1.15

Operating system:

Logs

Browser log

Nextcloud log

Browser log