Email filtering systems are dynamic and constantly evolve and adapt to new attacks.
1. Relay Black List (RBL)
Several RBL services (Spamhaus, Spamcop, Invaluement, etc.) are combined to allow different attack information to be cross-checked in real time (we are also contributors).
2. Multi-level allow and block lists
The administrator can centrally manage allow and block lists for their email domains. To allow or block a contact, you can specify either a full email address or an email domain.
Each user can also have their own allow and block lists.
3. Sender Verify
The server verifies that the sender actually exists on the MX server of the sending domain. This helps to avoid a lot of spam, but can also block some automatic emails (such as 'no reply').
This is why the authorisation list check is positioned upstream.
4. Incoming email filtering
Anti-virus filtering
Several anti-virus programmes (ClamAV, Eset, SpamAssassin, etc.) are combined to provide maximum protection. Each program is updated automatically several times a day.
Anti-spam filtering
Several anti-spam programmes are available, including SpamAssassin and the Cleanmail engine. Different modules are used for each one, such as Bayesian filtering with self-learning and a URL reputation module.
DMARC, DKIM and SPF checks are also used to validate the sender's email domain.
Anti-ad filtering
This filter identifies advertising emails with a prefix in the subject line, such as: [AD]
5. Milter behavioural filtering server
Alinto has developed various behavioural management filters.
These include limitations on incoming traffic by geographic area and email type.
Detection of abusive use, with the option to block and send an alert.