Greylisting : Information for System Administrators
First, if you are an end-user then this page will probably make no sense to you. Please ask the person responsible for your e-mail server to read it instead (this is usually your ISP or corporate IT department).
If you have arrived at this page after seeing a message similar to this one :
450 4.2.0 <firstname.lastname@example.org>: Recipient address rejected: Greylisted. See http://www.digitaldaemons.co.uk/greylist or contact email@example.com for whitelisting
then you are in the right place. As part of the endless battle to combat spam we have implemented a system known as greylisting on our mailservers. Basically, greylisting issues a temporary fail for all messages arriving at our servers from IP addresses & domains that have not sent us mail before. The principal is that real mailservers will resend the message, most spammers won't. A full explanation of how it works can be found here : http://en.wikipedia.org/wiki/Greylisting
Unfortunately, as with all anti-spam efforts it's not a perfect solution. In certain cases legitimate mail can be repeatedly held by greylisting, occasionally ending up being severely delayed or even lost. To combat this we operate a whitelist of providers that we know have problems with greylisting and which also send legitimate mail. If you are having problems getting e-mail through to us or one of our clients due to greylisting, please complete the form below and we will add your details to our whitelist.
Please be aware that whitelist additions are done manually and are checked before being approved - it can take 24-48 hours for your request to be processed.
Note to spammers : If you are listed at Spamhaus or use one of the many mailing list providers who don't operate confirmed opt-in policies please don't bother asking for whitelisting - it's not going to happen!