If the recipient is doing a hard check for valid SPF, you will fail because you have no SPF record:
We check for INVALID SPF records, but pass if there is no SPF record.
You also have a NAMESERVER (DNS) issue:
You have TWO nameservers listed with your DOMAIN NAME registrar:
ns1.dubai-hosting.net. | No Glue | TTL=3600
ns2.dubai-hosting.net. | No Glue | TTL=3600
but the only DNS server which responds is ns1.dubai-hosting.net on 126.96.36.199
This could be caused by the fact that both of your DNS servers appear to be on the same IP ADDRESS. DNS must be on different IP addresses and, for both redundancy and maximum availability, should be located on separate CLASS C subnets.
While this is, in and of itself, not a reason to bounce messages, it can be confusing to some mail servers and antispam checks and cause them to outright reject messages.
At least 2 (RFC2182 section 5 recommends at least 3), but fewer than 8 NS records exist (RFC1912 section 2.8 recommends that you have no more than 7). This meets the RFC minimum requirements, but is lower than the upper limits that some domain registrars have on the number of nameservers.
A larger number of nameservers reduce the load on each and, since they should be located in different locations, prevent a single point of failure.
Hope this helps you troubleshoot your issues.
If you still have problems resolving the problem, you can either open a ticket with SmarterTools or contact one of the techs on here for paid troubleshooting and support.
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