Dont know whats going on here, but it seems like a specific domain is being rewritten..
Look at the slt@ part, that should be a valid domain and by the looks of it, it was correct when mail was recieved. At some point it got rewritten to a number.
Fixed it for now I think by updating to 9.305-4 from 9.303-2
It is a big issue however cause bounce mails was never delivered to sender because of the invalid rewritten domain.
/var/log/smtp/2014/12/smtp-2014-12-20.log.gz:2014:12:20-12:30:20 ASG220SKA-1 smtpd[27297]: SCANNER[27297]: 1Y2IEm-00076H-AN replaced@replaced.com P= R=dnslookup T=remote_smtp: SMTP error from remote mail server after RCPT TO:: host mail.replaced@replaced.com [replaced]: 501 5.7.1 ... Sender domain must exist
/var/log/smtp/2014/12/smtp-2014-12-20.log.gz:2014:12:20-12:31:00 ASG220SKA-1 exim-out[27667]: 2014-12-20 12:31:00 1Y2IEo-00076c-1A ** slt@0431e6d08c: Unrouteable address
/var/log/smtp/2014/12/smtp-2014-12-20.log.gz:2014:12:20-12:31:00 ASG220SKA-1 exim-out[27667]: 2014-12-20 12:31:00 1Y2IEo-00076c-1A slt@0431e6d08c: error ignored
This thread was automatically locked due to age.