Error Seting Spf for mail Server

Solution 1:

There are a couple of things here. First, the error means that you have a specified in the SPF record, but there is no A record in your DNS entries, so either create an address record for the base domain or remove a from the SPF record.

Second, you mention that you have multiple servers that send, but mx is the only other entry in the SPF record as an authorized sender. This means that all of those servers that can send mail should be listed within your domain's MX records. If they are not part of the domain's MX records, you will need to list their individual IP addresses as part of the SPF entry to let others know they are authorized (v=spf1 mx ip4:1.2.3.4 -all if, for example, the IP address for mail.a.mydomain.ac.id were 1.2.3.4).

Solution 2:

You should create an A record for mydomain.ac.id in DNS