all mails going out easily beside one:
SMTP error from remote server for TEXT command, host: smtp.rzone.de (81.169.145.98) reason: 550 5.7.1 Refused by local policy. No SPAM please! (B-EX 149500::154053360
3-0000A5BA-E2F65BCD/10/4044493682) see https://www.strato.com/faq/en_u
s/article/2420
i checked the receiver; on his side evrything is ok