In the logfiles there is this error
25-02-2015 09:13:23 – FATAL – 11,3 MB – Duplicate entry ” for key 2
25-02-2015 09:14:28 – FATAL – 11,3 MB – Duplicate entry ” for key 2
25-02-2015 10:10:48 – FATAL – 11,2 MB – Duplicate entry ” for key 2
25-02-2015 10:11:34 – FATAL – 11,2 MB – Duplicate entry ” for key 2
25-02-2015 10:11:58 – FATAL – 11,1 MB – Duplicate entry ” for key 2
25-02-2015 10:39:31 – FATAL – 11,2 MB – Duplicate entry ” for key 2
25-02-2015 10:42:39 – FATAL – 11,2 MB – Duplicate entry ” for key 2
Wenn i delete the existing newsletters it works. For once, then i again have to delete the existing newsletter.