Greylistd
I've setup Greylistd to cut down on spam. It works like this:
When an email from an unknown email address sends mail to the server, it tells the server there was a temporary failure and writes the email to a db of some sort. A properly constructed email server will try again a moment or two later, resulting in the greylistd server permitting the mail, and any subsequent to pass through. A "standard" spam server won't try to resend the email resulting in the email not being put through.
This has been having minor problems with multiple outgoing SMTP servers, as when the first one fails it passes it over to the next one to try again. The server switch changes the IP and doesn't confirm the email address with Greylistd. Google is the biggest issue with that, and I've whitelisted *.google.com.
If you have any problems or concerns, comment or email me at graham.christensen@itrebal.com.
Graham
When an email from an unknown email address sends mail to the server, it tells the server there was a temporary failure and writes the email to a db of some sort. A properly constructed email server will try again a moment or two later, resulting in the greylistd server permitting the mail, and any subsequent to pass through. A "standard" spam server won't try to resend the email resulting in the email not being put through.
This has been having minor problems with multiple outgoing SMTP servers, as when the first one fails it passes it over to the next one to try again. The server switch changes the IP and doesn't confirm the email address with Greylistd. Google is the biggest issue with that, and I've whitelisted *.google.com.
If you have any problems or concerns, comment or email me at graham.christensen@itrebal.com.
Graham
