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If you were sent to this page, it is most likely because you have been directed here by the bounce back of an email you sent out.

Outblaze Limited hosts webmail services for several thousand domains, with userbases ranging from a few thousand to several million mailboxes. Our total userbase amounts to at least 40 million mailboxes.

1. Block Lists

Being a responsible email provider, Outblaze is obligated to protect its users from being spammed, and ensure a clean (as spam free as possible) environment for them. To this end, we block email from IP addresses/domains for various reasons.

Our "spamfilter" machines, which accept inbound mail for our domains, filter incoming mail against:

  1. A set of DNSBLs (DNS based Block Lists), of which we maintain regularly updated local mirrors. These DNSBLs include:

    Spamhaus SBL
    Spam sources
    Spamhaus XBL
    Compromised hosts
    Spamhaus PBL
    End-user hosts

    If you are listed by any of these, we request you to contact the maintainers of these sites directly.

  2. A local blocklist of known/potential spam source IPs and netblocks, known as the OBSL (Outblaze Spammers List). This includes known spam sources not otherwise listed in the various DNSBLs we use, as well as open relays which deliver spam to us.

    We also block mail from known dialup pools and other dynamic IP blocks, due to the ever present risk of "direct to MX" spam originating from spammers running bulkmailer software equipped with SMTP engine capablities, and "remailer" virii such as Sircam and Klez, which have their own SMTP engines to remail copies of themselves.

    A further check blocks mail from IP addresses which send us HELO strings associated with spam - such as forged HELOs, HELOs commonly generated by spam sending software etc.

  3. Several other known spam sources are blocked by name, in our "access database".

  4. Finally, chronic spam sources are blocked at our firewall (especially when they do not heed permanent bounce - or 550 - errors issued by our mailservers and repeatedly attempt to deliver email to our servers).

2. Open Relay Testing

For mail servers that have delivered email to our servers, if they fit the following criteria they are automatically tested for open relay. If our testing shows that these are open relays, they will be automatically blocked until they are fixed.

  1. deliver mail beyond a threshold quantity (counts, envelope senders, number of unknown users, past history of spewing spam)

  2. deliver mail with a sender envelope of Hotmail/Yahoo/other free email domains, but from an IP which does not have an rDNS identifying it as part of that domain. For example, mail claiming to be from @yahoo.com reaches us from a machine which actually happens to be in the netblock of a Korean university, rather than a Yahoo mail server. That mail server gets relay tested

After the technical component (above) comes the "human" component - our Postmaster, Security and Abuse team.

This team's roles include:

  1. Reading and responding to spam complaints from our users, and from the general public complaining about any of our users who spam
  2. Applying our (zero tolerance to spam) acceptable use policy (AUP) where applicable.
  3. Maintaining contacts with postmasters/sysadmins at other domains to resolve blocking issues (where we are blocking mail from their service, or they are blocking mail from our service for whatever reason) ASAP.
  4. Monitoring and participating in antispam newsgroups and mailing lists, in order to stay abreast of the spam situation, and also to develop and maintain good working relationships with postmasters, blocklist maintainers and other anti-spammers around the world.

If you need to contact our postmaster team, please feel free to mail them at postmaster@outblaze.com