SPF uses DNS records to define what IP addresses are allowed to send an email for a domain. This means that if your email is hosted by N2Net, you need to be sure that you are using the proper N2Net outbound (SMTP) email server to send all outbound mail. If you send an email using another SMTP server, the SPF will most likely cause the message to be marked as spam or rejected by the recipient.
DKIM also uses DNS records and an encryption-based digital signature to further verify that a message was sent through the proper SMTP server. As with SPF, please make sure that you are using the proper outbound SMTP email server for your email domain.