smtpout.dattobackup.com has no SRV records.
Question and response
Question
dig smtpout.dattobackup.com. SRV
Answer
The response has no answer records.
Authority
dattobackup.com. 3500 SOA ns1.dattobackup.com. dns.dattobackup.com. 2019119007 28800 7200 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0