Support - Spam Filters

Adhost uses SpamAssassin (http://spamassassin.apache.org) to block spam from our email users. You can adjust the filter level on your pop account(s) by logging into the Client Login (https://client.adhost.com) and selecting "Email Manager". From there, click on the link that says "Mail Filters" next to the pop account in question.

NOTE: Not all users will have access to the Adhost Client Login. Access to this web site (https://client.adhost.com) is normally given to the web sites administrator or owner of the account. If you don't have this access please contact the adminsitrator of your domain before contacting Adhost.

E-Mail Filter Help

This set of information and instructions are designed to assist you with the new Adhost email filtering system. You are now able to make changes to how your POP account handles the filter on mail.adhost.com through this interface.

VIRUS INFECTED EMAIL: By default, all email found to contain a virus will be quarantined, and a notification sent to the recipient. Our filtering system does allow you to force the system to send you the virus anyway, or even to disable virus checking entirely, but we strongly urge you NOT to use these options. While you should not expect the filter to catch ALL viruses (especially very new ones), it will catch the vast majority of them. Note that you should not allow this new filter to make you complacent. You should NEVER open an attachment that you have not specifically requested, even from someone you know. Also, we strongly recommend utilizing virus protection software on your desktop computer and updating it daily.
BANNED FILES: By default, files that can be run by your email client automatically, which may or may not contain viruses, are banned. These include files with suffixes .exe, .vbs, .pif, .scr, .bat, and .com. We suggest that if you need to send a file with such an extension, that you use the Zip utility to archive them first. This has the added benefit of making the email smaller, and thus easier to both send and receive.
Unsolicited Commercial Email (UCE or "spam"): By default, spam will be marked as such (with "****SPAM****" in the Subject, and a header that reads "X-Spam: Yes"), but the email will still be delivered to you. This marking will occur at the level where a setting of "Normal" would actually reject the email. (See section below on adjusting your settings.) Again, these settings are entirely configurable by you. Note that it is possible (and often desirable) to discard spam before it ever reaches your pop account. However,ADHOST IN NO CASE ACCEPTS RESPONSIBILITY FOR ANY DISCARDED OR UNDELIVERED MAIL REGARDLESS OF THE REASON FOR DISCARD OR FAILURE TO DELIVER. BY USING OUR MAIL SERVICES, AND ESPECIALLY OUR UCE/VIRUS FILTERING, YOU AGREE TO HOLD ADHOST HARMLESS AGAINST ANY LOSS OF DATA.
BAD HEADERS: What is an invalid character in mail headers? The RFC 2822 standard specifies rules for forming internet messages. It does not allow the use of characters with ASCII codes above 127 to be used directly (non-encoded) in mail header (it also prohibits NUL and bare CR). If characters (e.g. with diacritics) from ISO Latin or other alphabets need to be included in the header, these characters need to be properly encoded according to RFC 2047. This encoding is often done transparently by mail reader (MUA), but if automatic encoding is not available (e.g. by some older MUA) it is the user's responsibility to avoid the use of such characters in mail header, or to encode them manually. Typically the offending header fields in this category are 'Subject', 'Organization', and comment fields in e-mail addresses of the 'From', 'To' and 'Cc'. Sometimes such invalid header fields are inserted automatically by some MUA, MTA, content checker, or other mail handling service. If this is the case, that service needs to be fixed or properly configured. Typically the offending header fields in this category are 'Date', 'Received', 'X-Mailer', 'X-Priority', 'X-Scanned', etc. If the sender doesn't know how to fix or avoid the problem, they should report it to their postmaster or system manager.

Once the email has been scored, your user settings are read and the UCE is handled according to those settings. Again, the default will be "wants all spam", or, in other words, mark all spam but continue to send it. This default would allow you to use your email client's filtering to put all the UCE in a special folder for later review or deletion. It also will allow you to read the email headers to see the scores of various emails, which will help you to determine which default setting will work best for you, or if you need to create a custom filter configuration.

Please note that not all UCE is created equal and that a certain percentage of UCE will not match SpamAssassin's profiles. There is little we can do about this without risking marking legitimate mail as UCE (and hence running the risk of throwing away such mail). If you have particularly egregious UCE that you would like us to consider, please forward a copy of the mail, including all headers to abuse@adhost.com and we'll evaluate the mail and the possible need to adjust settings in the SpamAssassin configuration files.

In the Adhost Client Login, (https://client.adhost.com), you will be able to fully configure your mail filters by pop account. There are several standard settings and some special cases. If none of those seem to fit your needs, you can specifically configure each setting by using the "Custom" setting.

There are 4 "special" settings and 7 "standard" settings, plus "custom". The "standard" settings are basically the same (both spam and viruses are blocked), with the only differences being the levels at which spam actions are taken.

SPECIAL SETTINGS:
1. ) No Checks. No checks, no marks. You receive all mail.
2. ) Unblocked. Check (and mark) for spam and viruses, but send all anyway.
3. ) Wants all spam. Mark spam, but send it anyway. Block viruses.
4. ) Wants viruses (and banned files). Mark and block spam at "Normal" levels, but send all others.
STANDARD SETTINGS:
- Very Permissive: Blocks only the most egregious of spam. Almost no chance of blocked "good" mail.
- Permissive: A more generous setting that allows more spam through.
- Somewhat Permissive: Allows a bit more spam through to you than the Normal setting.
- Normal: Most spam is blocked, and most of the rest is marked. Very small chance of "good" mail being blocked.
- Somewhat Aggressive: Just a bit more aggressive than the Normal setting.
- Aggressive: Slightly more aggressive in blocking spam than the above.
- Very Aggressive: For the person who REALLY doesn't want any spam, and is willing to risk losing mail to make that happen.
All seven levels above have their flags set to N,N,N,N,N,N,N,N,Y, or "Check for viruses", "Don't send viruses", "Check for Banned Files","Don't send banned files", "Check for UCE","Don't send UCE marked above threshold", "Check for bad headers", "Don't send bad headers", and "Modify Subject if spam".
Here is what you will be able to configure if you use "Custom". There are 9 Yes/No (Y/N) flags that can be set:
- Bypass Virus Checks No virus check at all.
- Accept All Viruses Check but send viruses.
- Bypass Banned File Checks No banned file checks at all.
- Accept All Banned Files Check, but do not block banned files.
- Bypass UCE Checks No spam checks at all.
- Accept All UCE. Check but do not block UCE.
- Bypass Bad Header Checks Do not check for bad email headers at all.
- Accept All Bad Headers Check, but do not block email with bad headers.
- Modifies Subject to Indicate UCE Controls if "****SPAM****" is pre-pended to the Subject in addition to the "X-Spam: Yes" header line.
There are also 3 numerical values that can be set:
1. ) Tag UCE Level: This number (-999.9 to 999.9) determines when the email header tags will be written.
2. ) Mark UCE Level: This number (-999.9 to 999.9) determines the point at which the header "X-Spam: Yes" is added, and also possibly the Subject line is altered with "****SPAM****" pre-pended to it.
3. ) Drop UCE Level: This number (-999.9 to 999.9) specifies the point at which spam will be discarded. Note that setting this to 999 will mean, for practical purposes, you receive ALL spam. Note that level 1 MUST be less than or equal to level 2, which MUST be less than or equal to level 3.