Please bear in mind that the following SMTP servers have reported problems:
29.05.2023, 09:40:55 <opetrov@uni-ruse.bg>: host mx2.uni-ruse.bg[91.210.88.19] said: 554 5.7.1 We did not like your spam. Go away! rspamd.uni-ruse.bg (in reply to end of DATA command)