Mailshine is made up of a complex array of technologies that when used together in collaboration, are extremely effective. You’ve ended up on this page because you wanted to know the nitty0-gritty details so here you go:
We use the following methods to filter e-mail:

IP Block list, Rate Control (how many messages are sent per minute from a specific host), Virus Checking with archive decompression, second virus check, message signature check (similar to razor), Intention analysis (known spam messages based on content), Bayesian analysis (global/user), signature/fingerprint based scanning, OCR image recognition technologies, as well as regular expressions/rules.

Here is a list of the features our service offers:

Protection against e-mail borne threats:

Anti-Spam: All email—unless white listed—goes through a number of filters before being forwarded onto the client’s mail server.

Anti-virus: All messages—even from white listed domains or hosts—are scanned twice for virus threats. Archives are decompressed then scanned and all attachments are checked against our blacklist of file types.

Anti-spoofing: SPF support. Our service checks all sending domains for SPF (Sender Protection Framework) records within their DNS zone. If the domain contains an SPF record, our service will verify that the sending server is listed within the SPF record. See http://www.openspf.org/ for more information.

Anti-phishing: These are considered spam and are blocked in the same way.

Anti-spyware (attachments): All attachments are scanned for any executables containing spyware.

Denial of Service protection: we have rate controls in place to stop DoS as well as dictionary based spam attacks.

End user control features:

Personal allow and block lists: Each user can whitelist or blacklist e-mail addresses easily allowing messages to bypass spam filtering in the future. This feature requires the quarantine to be enabled for the domain.

Personal Bayesian database: Each user can train their individual Bayesian database allowing users to tailor the filtering for their specific needs. This feature requires the quarantine to be enabled for the domain.

End-user quarantine: Questionable e-mails—emails that may appear to be spam however do not achieve a high enough score to be blocked—can be directed to the quarantine mailbox where users can later visit to either deliver or delete the message.

Daily quarantine e-mail: An e-mail is sent out daily to all end-users with quarantine mailboxes summarizing the questionable messages. From this e-mail users can easily deliver, whitelist or delete a message.

Additional features of mention:

Mailbox verification: LDAP and Exchange support allow our systems to verify a mailbox exists before delivering the message. For those with SMTP gateways or hosts that support recipient verification via the RCP To: command, our service will verify mailboxes using this function.

Mailbagging: Our systems will “mailbag” messages for up to 48 hours in the event your mail server is down. When your server comes back up, our service will deliver the messages to you, transparent to your customers.

Message redelivery: After messages are delivered, they are stored for a number of days before being purged. This allows us to redeliver a message that has been accidentally deleted.

Availability: High availability is of utmost importance to us. Our servers are geographically in separate data centers. Highly available power and data connections ensure our services continue to run despite unplanned utility interruptions. With over 3 uplinks to the Internet, multiple backup UPS systems and generators (approved to run the data centre for months without power) you can rest assured your mail will be available. Even in an event where one data center experiences a complete outage, the Mailshine service is clustered to ensure our customers do not experience loss of service.

If you have additional questions, technical or not, please feel free to contact us directly.