The SPF record for the domain "embarqmail.com" only permits sending from:
;; ANSWER SECTION:
embarqmail.com. 60 IN TXT "v=spf1 a mx ip4:208.47.184.3 ip
4:208.47.184.5 ip4:208.47.184.7 ip4:205.219.233.9 ip4:208.47.184.9 ip4:205.219.2
33.7 include:centurylink.net ~all"
Are you mailing logs direct from your router? Your public IP address is not a permitted sender.
The good news is that CenturyLink has coded the SPF for a "softfail". Had they used. "-all", that would indicate a hard fail.
If you are sending through "smtp.embarqmail.com", then I am not sure why the softfail; unless they have incorrect information in their SPF record.