In order for your name to be able to send messages from Mailkit servers, it is necessary to authorize them in the SPF record of the domain by adding our SPF to your record. In the DNS settings of your domain, look for a TXT entry starting with "v = spf1" and fill in this entry "... include:spf.mailkit.eu ...".
If your domain does not have any SPF records, we recommend that you create this record in the form "v = spf1 mx include: spf.mailkit.eu ~ all"
ATTENTION: Each domain can only contain ONE SPF record! Therefore, it is not permissible to have multiple SPF records, but all permissions must be in one SPF record. This record must not exceed the 10 DNS nesting limit, so its length is required. Of course, this has not only practical reasons but also security - you do not want to allow half of the internet. So be careful what is allowed in your domain and whether your SPF records are fully valid. We recommend using it for review SPF analysis on Dmarcian.com.
The topic of SPF records is more fully covered by an article on our blog.