Error when adding external user

[JiriMON]

Steps to reproduce

1. Email setup with SMTP send mode in admin additional settings,
2. SMTP server with "Reject if SMTP AUTH is different from sender" feature on.
3. Click sharing on a folder
4. Enter external email address

Expected behaviour

Two emails should be generated automatically without error.

Actual behaviour

• Got error message: "Expected response code 250 but got code "501", with message "501 5.7.1 ... Permission denied ""
• Email with link to share is send via SMTP account setup in admin area.
• Server tries to send password email with FROM: header as current logged user
  In case SMTP is setup with "Reject if SMTP AUTH is different from sender" the email password is not send, because FROM: is set to current user, however AUTH to server is set according email settings in additional settings

Server configuration

Operating system: Linux nextcloud 4.4.0-81-generic #104-Ubuntu SMP Wed Jun 14 08:17:06 UTC 2017 x86_64

Web server: Apache/2.4.18 (Ubuntu) (apache2handler)

Database: mysql 5.7.18

PHP version: 7.0.18-0ubuntu0.16.04.1
Modules loaded: Core, date, libxml, openssl, pcre, zlib, filter, hash, Reflection, SPL, session, standard, apache2handler, redis, mysqlnd, PDO, xml, calendar, ctype, curl, dom, mbstring, fileinfo, ftp, gd, gettext, iconv, imap, intl, json, ldap, exif, mcrypt, mysqli, pdo_mysql, pdo_pgsql, pdo_sqlite, pgsql, Phar, posix, readline, shmop, SimpleXML, smbclient, sockets, sqlite3, sysvmsg, sysvsem, sysvshm, tokenizer, wddx, xmlreader, xmlwriter, xsl, zip, libsmbclient, Zend OPcache

Nextcloud version: 12.0.0 - 12.0.0.29

Updated from an older Nextcloud/ownCloud or fresh install: update from 11

Where did you install Nextcloud from: Official VM

[]

List of activated apps:

App list

``` Enabled: - activity: 2.5.2 - admin_audit: 1.2.0 - bookmarks: 0.10.0 - bruteforcesettings: 1.0.2 - calendar: 1.5.3 - circles: 0.11.0 - comments: 1.2.0 - contacts: 1.5.3 - dav: 1.3.0 - deck: 0.2.0 - drawio: 0.8.8 - federatedfilesharing: 1.2.0 - files: 1.7.2 - files_accesscontrol: 1.2.4 - files_automatedtagging: 1.2.2 - files_downloadactivity: 1.1.1 - files_external: 1.3.0 - files_pdfviewer: 1.1.1 - files_retention: 1.1.2 - files_sharing: 1.4.0 - files_texteditor: 2.4.1 - files_trashbin: 1.2.0 - files_versions: 1.5.0 - files_videoplayer: 1.1.0 - firstrunwizard: 2.1 - gallery: 17.0.0 - groupfolders: 1.0.2 - impersonate: 1.0.1 - issuetemplate: 0.2.1 - logreader: 2.0.0 - lookup_server_connector: 1.0.0 - nextant: 1.0.8 - notes: 2.2.0 - notifications: 2.0.0 - oauth2: 1.0.5 - ojsxc: 3.2.1 - password_policy: 1.2.2 - provisioning_api: 1.2.0 - quota_warning: 1.0.0 - rainloop: 5.0.0 - richdocuments: 1.12.33 - serverinfo: 1.2.0 - sharebymail: 1.2.0 - spreed: 2.0.1 - spreedme: 0.3.9 - survey_client: 1.0.0 - systemtags: 1.2.0 - tasks: 0.9.5 - theming: 1.3.0 - twofactor_backupcodes: 1.1.1 - updatenotification: 1.2.0 - user_external: 0.4 - user_ldap: 1.2.1 - workflowengine: 1.2.0

Disabled:

• announcementcenter
• encryption
• external
• federation
• mail
• nextcloud_announcements
• ocr
• sensorlogger
• user_saml

</details>

**The content of config/config.php:**
<details>
	<summary>Config report</summary>

{
"passwordsalt": "REMOVED SENSITIVE VALUE",
"secret": "REMOVED SENSITIVE VALUE",
"trusted_domains": [
"cloud.gmproject.cz",
"10.0.0.226"
],
"datadirectory": "/var/ncdata",
"overwrite.cli.url": "https://cloud.gmproject.cz/",
"dbtype": "mysql",
"version": "12.0.0.29",
"dbname": "nextcloud_db",
"dbhost": "localhost",
"dbport": "",
"dbtableprefix": "oc_",
"dbuser": "REMOVED SENSITIVE VALUE",
"dbpassword": "REMOVED SENSITIVE VALUE",
"logtimezone": "UTC",
"installed": true,
"instanceid": "ocy9r9oj7fyg",
"appstore.experimental.enabled": "true",
"mail_smtpmode": "smtp",
"mail_smtpauth": 1,
"mail_smtpport": "25",
"mail_smtphost": "ms.gmproject.cz",
"mail_smtpauthtype": "LOGIN",
"mail_from_address": "cloud",
"mail_domain": "gmproject.cz",
"mail_smtpname": "REMOVED SENSITIVE VALUE",
"mail_smtppassword": "REMOVED SENSITIVE VALUE",
"preview_libreoffice_path": "/usr/bin/libreoffice",
"memcache.local": "\OC\Memcache\Redis",
"filelocking.enabled": true,
"memcache.distributed": "\OC\Memcache\Redis",
"memcache.locking": "\OC\Memcache\Redis",
"redis": {
"host": "/var/run/redis/redis.sock",
"port": 0,
"timeout": 0,
"dbindex": 0
},
"maintenance": false,
"ldapIgnoreNamingRules": false,
"ldapProviderFactory": "\OCA\User_LDAP\LDAPProviderFactory",
"loglevel": 2,
"updater.release.channel": "stable",
"htaccess.RewriteBase": "/",
"theme": ""
}

</details>

**Are you using external storage, if yes which one:** Array
(
   
    [10] => \OCA\Files_External\Lib\Storage\SMB
    [11] => \OCA\Files_External\Lib\Storage\SMB
)


**Are you using encryption:** no


</details>
### Client configuration
**Browser:** Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_5) AppleWebKit/603.2.4 (KHTML, like Gecko) Version/10.1.1 Safari/603.2.4

[JiriMON]

Duplicates #5302