I have installed SPF on rhel 7.4. When spf trying to contact the sender, sometime it gives the message
NOQUEUE REJECT RCPT To … SERVER CONFIGUERATION PROBLEM… mails are rjected by spf. and also timeout error…
Taking too much time…
How to avoid that>>???
Checking SPF is directly related to speed of resolving DNS requests.
Then you need to set a suitable DNS server in DNR.