In the last week we have made a couple of tweaks to the email platform to better our spam detection, these tweaks involve checking if the sending email domain has the appropriate records to send email.
We ask that anyone sending emails to our domains (virginmedia.com, blueyonder.co.uk, ntlworld.com, virgin.net), make sure your domain has the basic records needed which include SPF and/or DMARC. SPF is the more common of the two and we will enforce greylisting if a domain has none.
What is greylisting?
Greylisting means we temporarily reject an incoming mail from a domain that hits our specified criteria (mentioned above), we basically let the sending server know they need to try again later, normally an email server set up correctly will retry the email again automatically (the time frame can vary, it is dependent upon the sending email server).
Why are we doing this?
It is best practice to always have a correctly set up email server, as this will give the best chances of delivery, as spam protection mechanisms will be able to correctly identify the email as legitimate. We are noticing an increasing amount of spam campaigns that do not do this, so this is our way of detecting and deterring them.
I know this is quite a shock as some email senders are used to not needing this (even though it allows spammers to freely abuse their domains) but we are trying to protect our customers and feel this small change will help that. We do plan to make further changes but we will now start slowly and ramp it up as we go.