Sender Policy Framework (SPF) is an optional validation technology that mail servers can use to determine if a server sending email for a domain is authorised to do so. Publishing a SPF record for your domain can help prevent spoofed (impersonated) email from received. Since SPF is an optional mechanism it cannot prevent spoofing but is a useful approach to enable mail servers to make informed decisions on how to handle email 'from' your domain.
If you host your DNS and mailboxes with Iridis we will automatically create an appropriate SPF record when your hosting is provisioned. If you use third party DNS or use one of our SMTP mail services (e.g. mailMX, mailRelay, mailFeed) we recommend that you create or update your SPF record. Before creating the record it is important to understand where email originates from for your domain as this will impact the record you should specify.
If email from your domain exclusively originates from Iridis mail services and/or your mail server you should create a TXT record in DNS with the following 'data' value specified:
v=spf1 a mx include:spf.uksmtp.co.uk -all
If a hostname is requested specify '@', this will ensure the record is create for your domain (e.g. example.com) rather than a sub-domain.
When creating the SPF record please consider instances such as where your website generates email and is hosted with a third party. In this scenario you will either need to add an additional 'include' if they publish an SPF record or add specific references for the associated IP address (e.g. ip4:10.20.30.40). For example, if your mail server or third party server IP address is 10.20.30.40 you may wish to specifically incorporate it:
v=spf1 a mx ip4:10.20.30.40 include:spf.uksmtp.co.uk -all
It is important to note that standards restrict the number of DNS lookups within the SPF record to 10. If your SPF record, including any referenced SPF records, exceed 10 DNS lookups it will be considered invalid.
Before publishing your record you can validate it using a number of third party websites including:
http://www.kitterman.com/spf/validate.html
For further information relating to SPF visit the project website at:
http://www.openspf.org
Joined before August 2018?
If you joined before August 2018 your SPF record may be:
v=spf1 a mx include:spf.mail.hosting-platform.com -all
This record remains valid and will be maintained for the forseeable future.