To enable the Calenso E-mail server to send e-mail messages (appointment confirmations and reminders) to customers on behalf of a Whitelabel domain, an SPF entry for Calenso must be made in the DNS settings of the Whitelabel domain.

SPF TXT Entry for Calenso

v=spf1 a mx ip4: ~all


The entry must be created in the DNS settings of the Whitelabel domain. The DNS settings are the settings for the domain e.g.

Example of an entry in the DNS server settings:

Is the SPF entry mandatory?

Calenso's e-mail sending will work even without the SPF entry. However, Calenso cannot guarantee that the email messages will reach the recipients. As without the SPF entry (permission of the Whitelabel domain), they are often marked as spam messages.

What is an SPF entry?

With the help of an SPF entry, you can enter computers and servers authorised to send mail into your DNS zone. The Sender Policy Framework (SPF) is intended to prevent the forgery of sender addresses for mails.

An SPF record is recorded as a TXT record for the domain that is to provide an SPF record. The SPF record can contain IP addresses or DNS records (A, AAAA, MX, etc.). A meaningful SPF record starts with


, followed by the specification of the authorised servers and the final instruction as to what should happen to servers not listed.