With try and error I find out if I delete the first of the X-Notes-Item entries msg.defects are empty! The content of this field is:
X-Notes-Item: =?UTF-8?B?Q2hpbGRfT3V0Z29pbmdfMDA0RThFQjdbTG9jYWxdIGJ5IG5sbm90ZXMuZXhl?= =?UTF-8?B?IG9uIE1hcmNvIEVpY2hlbGJlcmcoUmVsZWFzZSAxMi4wLjJGUDR8TWF5IDA2?= =?UTF-8?B?LCAyMDI0KSBhdCAyMC4wMy4yMDI1IDE1OjE4OjAz?=, =?UTF-8?B?U2VuZGluZyBzZXBhcmF0ZSB1cGRhdGVzIGZvciBlYWNoIHJ1bltMb2NhbF0g?= =?UTF-8?B?Ynkgbmxub3Rlcy5leGUgb24gTWFyY28gRWljaGVsYmVyZyhSZWxlYXNl?= =?UTF-8?B?IDEyLjAuMkZQNHxNYXkgMDYsIDIwMjQpIGF0IDIwLjAzLjIwMjUgMTU6MTg6?= =?UTF-8?B?MDM=?=, =?UTF-8?B?T0EoVXBkYXRlKVtMb2NhbF0gYnkgbmxub3Rlcy5leGUgb24gTWFyY28=?= =?UTF-8?B?IEVpY2hlbGJlcmcoUmVsZWFzZSAxMi4wLjJGUDR8TWF5IDA2LCAyMDI0KSA=?= =?UTF-8?B?YXQgMjAuMDMuMjAyNSAxNToxODowMw==?=, =?UTF-8?B?Q1MgTm90aWNlIGNvbnZlcnRlZCB0byBpQ2FsZW5kYXIgZm9ybWF0W0xvY2Fs?= =?UTF-8?B?XSBieSBSb3V0ZXIgb24gZG9taW5vKFJlbGVhc2UgMTQuMEZQMyBIRjE3fA==?= =?UTF-8?B?RGVjZW1iZXIgMTcsIDIwMjQpIGF0IDIwLjAzLjIwMjUgMTU6MTg6MDQ=?=; type=501; flags=0; name=$CSTrack
May be a special character ist the problem? Thank you!