We host a mail server, and many of our clients email various domains hosted by GoDaddy. Our issue is that on occasion when a client sends an email, it appears that the recipient's DNS server does not respond to our initial query. The client gets a bounce back message "450 4.1.2 <firstname.lastname@example.org>: Recipient address rejected: Domain not found" In most cases, they can resend the email a couple minutes later and it gets delivered without issue. If we run a "dig <domain> MX" command at the time we get a SERVFAIL status. We have tried several things with our mail server, used a different mail server, and switched between our DNS server and Google's DNS (184.108.40.206) to no avail. We are looking for any suggestions on why a mail server would not respond to our DNS query one minute, and a couple minutes later not have any issues. Thank you in advance for any suggestions.