Cannot add mailhandler-source

Hi,

I am using Drupal Commons 7.x-3.17 and installed Mailhandler on it (with all necessary dependencies). If I follow the Install.txt step by step and using the example "Mailhandler quick-start" and try to add a new mailhandler-source I get (if I use "Test mailbox") the following messages:

• mailbox was checked and contained 1 messages.
• User could not be authenticated. Please check your Mailhandler authentication plugin settings.
• Could not retrieve title from feed.

If I otherwise go to admin/structure/mailhandler and do "Test connection" with the "Test mailbox" I get an AJAX error (always nice to have):

An AJAX HTTP error occurred.
HTTP Result Code: 200
Debugging information follows.
Path: /commons/admin/structure/mailhandler/list/test_mailbox/test?token=qew3NrLaj27sScvYJoTxqhmXr6iUCt0DDow75pqFi_c
StatusText: OK
ResponseText: [{"command":"settings","settings":{"basePath":"\/commons\/","pathPrefix":"","ajaxPageState":{"theme":"ember","theme_token":"IvCib7DUngsqPFAlBDpnXHoKMNr1sN2rdlXmABjnkQQ"},"custom_search":{"form_target":"_self","solr":0},"tableHeaderOffset":"Drupal.navbar.height"},"merge":true},{"command":"insert","method":"replaceWith","selector":"#ctools-export-ui-list-items","data":"\u003Cdiv id=\u0022mailhandler_test_results\u0022 class=\u0022form-wrapper\u0022\u003E\u003Cdiv class=\u0022messages status\u0022\u003EMailhandler was able to connect to the mailbox.\u003C\/div\u003E\u003Cdiv class=\u0022messages status\u0022\u003EThere are 1 messages in the mailbox folder.\u003C\/div\u003E\u003C\/div\u003E\u003Ctable id=\u0022ctools-export-ui-list-items\u0022 class=\u0022sticky-enabled\u0022\u003E\n \u003Cthead\u003E\u003Ctr\u003E\u003Cth class=\u0022ctools-export-ui-title\u0022\u003ETitle\u003C\/th\u003E\u003Cth class=\u0022ctools-export-ui-name\u0022\u003EName\u003C\/th\u003E\u003Cth class=\u0022ctools-export-ui-storage\u0022\u003EStorage\u003C\/th\u003E\u003Cth class=\u0022ctools-export-ui-operations\u0022\u003EOperations\u003C\/th\u003E \u003C\/tr\u003E\u003C\/thead\u003E\n\u003Ctbody\u003E\n \u003Ctr class=\u0022ctools-export-ui-enabled odd\u0022\u003E\u003Ctd class=\u0022ctools-export-ui-title\u0022\u003Evertragsengel_imap\u003C\/td\u003E\u003Ctd class=\u0022ctools-export-ui-name\u0022\u003Eimap_de\u003C\/td\u003E\u003Ctd class=\u0022ctools-export-ui-storage\u0022\u003ENormal\u003C\/td\u003E\u003Ctd class=\u0022ctools-export-ui-operations\u0022\u003E\u003Cdiv class=\u0022ctools-no-js ctools-dropbutton ctools-button\u0022 id=\u0022ctools-button-1\u0022\u003E\u003Cdiv class=\u0022ctools-link\u0022\u003E\u003Ca href=\u0022#\u0022 class=\u0022ctools-twisty ctools-text\u0022\u003Eopen\u003C\/a\u003E\u003C\/div\u003E\u003Cdiv class=\u0022ctools-content\u0022\u003E\u003Cul class=\u0022\u0022\u003E\u003Cli class=\u0022test first\u0022\u003E\u003Ca href=\u0022\/commons\/admin\/structure\/mailhandler\/list\/imap_de\/test?token=qew3NrLaj27sScvYJoTxqhmXr6iUCt0DDow75pqFi_c\u0022 class=\u0022use-ajax\u0022\u003ETest connection\u003C\/a\u003E\u003C\/li\u003E\n\u003Cli class=\u0022edit\u0022\u003E\u003Ca href=\u0022\/commons\/admin\/structure\/mailhandler\/list\/imap_de\/edit\u0022\u003EEdit\u003C\/a\u003E\u003C\/li\u003E\n\u003Cli class=\u0022disable\u0022\u003E\u003Ca href=\u0022\/commons\/admin\/structure\/mailhandler\/list\/imap_de\/disable?token=Cn9kqSezvyMQvX9ry0Gzo8JlKlQC_Ym_7QTq3LBp200\u0022 class=\u0022use-ajax\u0022\u003EDisable\u003C\/a\u003E\u003C\/li\u003E\n\u003Cli class=\u0022delete\u0022\u003E\u003Ca href=\u0022\/commons\/admin\/structure\/mailhandler\/list\/imap_de\/delete\u0022\u003EDelete\u003C\/a\u003E\u003C\/li\u003E\n\u003Cli class=\u0022clone\u0022\u003E\u003Ca href=\u0022\/commons\/admin\/structure\/mailhandler\/list\/imap_de\/clone\u0022\u003EClone\u003C\/a\u003E\u003C\/li\u003E\n\u003Cli class=\u0022export last\u0022\u003E\u003Ca href=\u0022\/commons\/admin\/structure\/mailhandler\/list\/imap_de\/export\u0022\u003EExport\u003C\/a\u003E\u003C\/li\u003E\n\u003C\/ul\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/td\u003E \u003C\/tr\u003E\n \u003Ctr class=\u0022ctools-export-ui-enabled even\u0022\u003E\u003Ctd class=\u0022ctools-export-ui-title\u0022\u003ETest mailbox\u003C\/td\u003E\u003Ctd class=\u0022ctools-export-ui-name\u0022\u003Etest_mailbox\u003C\/td\u003E\u003Ctd class=\u0022ctools-export-ui-storage\u0022\u003EDefault\u003C\/td\u003E\u003Ctd class=\u0022ctools-export-ui-operations\u0022\u003E\u003Cdiv class=\u0022ctools-no-js ctools-dropbutton ctools-button\u0022 id=\u0022ctools-button-2\u0022\u003E\u003Cdiv class=\u0022ctools-link\u0022\u003E\u003Ca href=\u0022#\u0022 class=\u0022ctools-twisty ctools-text\u0022\u003Eopen\u003C\/a\u003E\u003C\/div\u003E\u003Cdiv class=\u0022ctools-content\u0022\u003E\u003Cul class=\u0022\u0022\u003E\u003Cli class=\u0022test first active\u0022\u003E\u003Ca href=\u0022\/commons\/admin\/structure\/mailhandler\/list\/test_mailbox\/test?token=qew3NrLaj27sScvYJoTxqhmXr6iUCt0DDow75pqFi_c\u0022 class=\u0022use-ajax active\u0022\u003ETest connection\u003C\/a\u003E\u003C\/li\u003E\n\u003Cli class=\u0022edit\u0022\u003E\u003Ca href=\u0022\/commons\/admin\/structure\/mailhandler\/list\/test_mailbox\/edit\u0022\u003EEdit\u003C\/a\u003E\u003C\/li\u003E\n\u003Cli class=\u0022disable\u0022\u003E\u003Ca href=\u0022\/commons\/admin\/structure\/mailhandler\/list\/test_mailbox\/disable?token=Cn9kqSezvyMQvX9ry0Gzo8JlKlQC_Ym_7QTq3LBp200\u0022 class=\u0022use-ajax\u0022\u003EDisable\u003C\/a\u003E\u003C\/li\u003E\n\u003Cli class=\u0022clone\u0022\u003E\u003Ca href=\u0022\/commons\/admin\/structure\/mailhandler\/list\/test_mailbox\/clone\u0022\u003EClone\u003C\/a\u003E\u003C\/li\u003E\n\u003Cli class=\u0022export last\u0022\u003E\u003Ca href=\u0022\commons\/admin\/structure\/mailhandler\/list\/test_mailbox\/export\u0022\u003EExport\u003C\/a\u003E\u003C\/li\u003E\n\u003C\/ul\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/td\u003E \u003C\/tr\u003E\n\u003C\/tbody\u003E\n\u003C\/table\u003E\n","settings":null}]
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I don't know what to do now, I tested my own mail settings, which seem to work in the way that the login data seem to be correct, but I also receive that AJAX error and the same messages for mailhandler-source (except of number 2). PHP IMAP library is also installed on the server. Please help. Thanks

P.S.: @moderators: Can you please delete (or hide) the first versions of this post??