If your Exim mail logs show the following error: Access denied – Invalid HELO name (See RFC2821 4.1.1.1) This means that the sending server’s HELO/EHLO hostname is invalid or misconfigured according to the SMTP protocol requirements. What is HELO / EHLO? When an email server connects to another via SMTP, it introduces itself with the … Read more
In this guide you will learn how to tweak the default postfix configuration for incoming emails. In Postfix configuration you need to add or edit following directives on /etc/postfix/main.cf configuration file. All configuration directives are explained in the postfix website. Postfix Configuration Parameters smtpd_helo_required = yes Require that a remote SMTP client introduces itself with … Read more
Using RBL is really efficient and pretty lightweight. All it take is some DNS queries and if you were going to receive a lot of spam email from the same client, this DNS entries will be cached in your (local) DNS. To get some figures on how many emails get caught through, on a server … Read more
IPs or domains that cause threat to your inboxes will be listed by the blacklists. If you are on a blacklist you should not keep quite you must act quickly. There are several email blacklists which tries to impress you with a long list, which might not be good tool. So, here is a list … Read more