SRO Hosting - Premium web hosting services  Why was my email blocked?

It is SRO Hosting's goal to provide the most reliable hosting service available, including "spam free" (to the extent possible) email service. While it is not possible to stop all spam and retain usable email service, there are ways to reduce it. To do this, SRO employs the following spam prevention techniques :

Local Blacklist ( 451 ... [ISP] blocked due to spam)
All SRO mail servers have a local blacklist used to block email from sources which have previously sent spam to that server. If your email bounced with error 451, forward it to your mail administrator. Administrators who contact us with evidence a spammer has been dealt with will have their server removed from the blacklist.

Remote IP Blacklist (553 Message rejected...)
SRO uses single IP RBL blacklists to block mail from open relays (allow anyone to spam from them) or servers listed as spam sources by reliable sources. If your email bounced with error 553, the bounce message will name the blacklist. Forward it to your mail administrator for resolution.

Grey Listing
SRO employs 'adaptive-greylisting' to block most "bot generated" spam. Greylisting rejects the first mail from an unknown source with a temporary failure until the sender tries again (as properly configured mail servers do). When the sender tries again, they are 'whitelisted' and their email allowed. This works because spam bots generally send huge volumes of mail once and never try again. Those who do retry later will often be blacklisted by then due to the spam they already sent to other spam reporting servers. Note: SRO greylisting white-lists many well known ISP and mailing list sources (Banks, governments,eBay, Paypal, Gmail) so their mail will not be delayed.

Bayesian Analysis (X-Spam-Status: ....)
SRO does not 'keyword' filter email. Our servers use custom Spamassassin probability ratings trained and tuned to our users email. We reject only the most obvious spam, quarantine "probable" spam and tag and deliver "likely" spam. Users may request adjustment or exclusion from Spamassassin filtering.   Quarantined mail is reviewed prior to deletion to check for false positives and adjust our filtering accordingly.

SPF listing
To prevent address forgery and joe jobs, mail addressed as originating from domains which employ SPF (Sender Policy Framework) may be tested against SPF records and rejected if the sending server is not listed as an allowed sender for that domain. For more information, see

All incomming mail is virus scanned. Emails with attached viruses are quarantined and discarded after one month. SRO will never bounce viruses.

Please see our spam policy for more information.
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