No connection to mail server and [IMAP] The folder "/Public" cannot be opened. (NO [NOPERM]

Support
16

http://mxtoolbox.com shows me:

image
image1560×564 72.4 KB 

Connecting to 89.58.xxx.xxx

220 mail.myserver.de ESMTP Postfix [213 ms]
EHLO keeper-us-east-1b.mxtoolbox.com
250-mail.myserver.de
250-PIPELINING
250-SIZE 100000000
250-VRFY
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN [204 ms]
MAIL FROM:<supertool@mxtoolboxsmtpdiag.com>
250 2.1.0 Ok [211 ms]
RCPT TO:<test@mxtoolboxsmtpdiag.com>
554 5.7.1 <test@mxtoolboxsmtpdiag.com>: Relay access denied [210 ms]

LookupServer 1748ms