Problem with MDaemon IMAP

I have MDaemon POP3/IMAP/SMTP server which is working flawless with Outlook 2010-2016. Now I’m trying to make it work with Delta.Chat with no luck. SMTP works fine and messages go out. But IMAP do nothing.

MDaemon log:
Tue 2019-05-14 20:34:06.698: 01: [967358] Session 967358; child 0003
Tue 2019-05-14 20:34:06.698: 05: [967358] Accepting IMAP connection from [XXX:42481] to [YYY:993]
Tue 2019-05-14 20:34:06.730: 01: [967358] SSL negotiation successful (TLS 1.2, 256 bit key exchange, 256 bit AES encryption)
Tue 2019-05-14 20:34:06.730: 03: [967358] --> * OK ZZZ IMAP4rev1 ready
Tue 2019-05-14 20:34:06.738: 02: [967358] <-- 1 LOGIN “YYY” ******
Tue 2019-05-14 20:34:06.741: 03: [967358] --> 1 OK LOGIN completed
Tue 2019-05-14 20:34:06.749: 05: [967358] Socket connection closed by the other side (how rude!)
Tue 2019-05-14 20:34:06.750: 01: [967358] IMAP session terminated, (Bytes in/out: 583/1686)
Tue 2019-05-14 20:34:06.750: 01: ----------

Delta Chat log says all the time the same:
05-14 20:33:22.017 9860 9883 I DeltaChat: 0 mails read from “DeltaChat”.
05-14 20:33:22.018 9860 9882 I DeltaChat: 0 mails read from “INBOX”.

Whats the problem?

Which version of Delta chat are you using? on which platform? which version of the core does it use(that can be found as first thing in the logs or on an about page)?

device=Xiaomi Redmi 4X (santoni)
android=7.1.2 (V10.3.1.0.NAMMIXM, N2G47H)
applicationId=chat.delta
app=Delta Chat 0.304.0-gplay
deltachat_core_version=v0.43.0
sqlite_version=3.26.0
compile_date=May 7 2019, 17:43:18