Email authentication at Umbler
Messages sent through Umbler's servers use SPF (Sender Policy Framework). This protocol ensures the delivery of the information, based on a secure communication between the sender's server and the recipient's server.
When receiving a message, the recipient's mail server checks if the sender's server has the authority to send messages on his behalf, if he can't confirm this information the message is usually put on the SPAM folder.
Please find below a brief explanation on the 3 most used methods for mail send authentication and why we use SPF.
SPF or Sender Policy Framework is an email validation protocol designed to detect and block email spoofing by providing a mechanism to allow receiving mail exchangers to verify that incoming mail from a domain comes from an IP Address authorized by that domain's administrators.
Umbler's SPF: v=spf1 include:spf.umbler.com ~all
If an SPF record was already configured for your domain and you wish to allow another service to send mail messages on your behalf, using your domain, like Sendgrid, Mailee.me or Mailgun you have to edit your current record, appending the info of the new service to your existing SPF record.
Edit the base information in your SPF record (from v=spf1 to ~all) keep the Umbler information and just add the new information from the new service, like in these examples:
v=spf1 include:spf.umbler.com include:_spf.mailee.me ~all
v=spf1 include:spf.umbler.com include:mailgun.org ~all
We don't currently implement this solution, as it requests every message to be signed by our servers, and if a client doesn't have his DNS records configured accordingly, it would inflict a high penalty on his spam reputation.
This configuration uses encryption with DNS public keys, checking the headers of the message, resulting in a very high usage of processing power for both the sender's mail server and the recipient's.
We at Umbler are studying ways to implement DKIM more efficiently, we are still working hard on it, but still don't have a estimated time for delivery yet.