You are unable to send emails to 3rd party domains , you receive a bounce back message saying : 533 5.7.1 Your SPF entry has an error - Please contact with your IT team.
Release : 10.7.3
Component : Default-Sym
Check Your SPF record as it might be exceeding the number of allowed lookup.
The Sender Policy Framework (SPF) specification has a limit of the DNS lookup up to (10) required to fully resolve an SPF record. This limit helps reduce the amount of resources used by mailbox providers when checking SPF records. If you exceed this limit, you will fail an SPF check.
See RFC 7208 https://tools.ietf.org/html/rfc7208