I cannot send emails to Gmail addresses, the messages are rejected. Why?
Google has recently started rejecting messages from email addresses that lack SPF and/or DKIM entries. Attempts to send email to Gmail addresses from email addresses on a domain name without SPF / DKIM will give an error message and the email will not reach the recipient.
For domains that have both e-mail and DNS through Domainnameshop, we will automatically set up correct SPF and DKIM records for you, but if you have your e-mail or name servers with another provider, you must make sure yourself that SPF and DKIM are correctly configured. See explanation here .