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Posted by [ISS] Justin Doyle on 30 September 2013 03:55 PM

We are in the process of moving to a new e-mail system - DCU Apps. The move to the new system will involve a change in how we scan DCU e-mail for spam and viruses. The full technical details of the changes are detailed further below.

In summary, until the migration is complete for all accounts we must continue to use the old DCU system for scanning e-mail. The performance of this old system has been very good over the years. However, in the last couple of years the amount of spam not caught by the system has increased. Once the migration is fully complete for all staff e-mail accounts, e-mail scanning will be incorporated with the new e-mail system. Until then, spam scanning may be less than optimal.

Technical Details

The statistics in the chart below summarise the volume of e-mail scanned in DCU since 2006. Approximately 81.5% of all DCU e-mail is rejected as spam before being accepted onto the DCU network. The remaining e-mail (8.5%) is scanned and filtered accordingly (clean & quarantined messages).

Spam & Virus Scanning Stats

E-mail Scanning

E-mail scanning in DCU is currently performed in two phases:

Phase 1) Technical Checks - 81.5% of all DCU e-mail rejected at this stage

  • Reject all invalid DCU address (4%)
  • Reject all e-mails from blacklisted senders (58%)
  • Reject all e-mails from senders who do not meet e-mail standards (29.5%)

Phase 2) Spam & Virus Scan - 8.5% of email accepted onto DCU network to be filtered

  • Quarantine all remaining spam and virus messages (3%)
  • Deliver 'clean' e-mails to DCU mailboxes (5.5%)

Of the 5.5% of e-mail which is considered clean, some messages may be spam. No spam scanning technology is 100% accurate, and there will always be some mails in this category. However, the number of these 'false negative' messages is currently slightly higher than it should be in DCU. The proportion of e-mails in this category will be significantly reduced once the e-mail migration process is complete.

Email Routing & Spam Scanning

Before migration:

During migration:

After migration: