Frequently Asked Questions
Category Spam Blocking, Mail Options
The mail system distinguishes between addresses that are used for delivery (envelope addresses, i.e. what would be written on an envelope) and what is written as an "address" in the message itself. The latter corresponds to what is written on a letterhead, can be completely fictitious and is not used for delivery and is the only thing a mail program displays. I.e. a received message does not necessarily indicate whether the message was addressed to a certain address. Conversely, however, if the message ends up with one, then it must have been addressed accordingly. Misdirected delivery does not exist.
This behavior is thus the source of confusion and disbelief, which spammers, phishers and others with their fictitious messages skillfully exploit. Everything that is displayed in the letterhead (mail header) is de facto arbitrarily falsifiable. Only in the usually not displayed "details" of a message ("all headers" etc.) you will find certain information regarding the origin and occasionally also the recipient.
The individual email options, opens an external URL in a new window for a person contains the appropriate setting. This is the value Ignore SPAM level, which is set to 0 for the corresponding delivery address. This causes all mails sent to the respective delivery address from outside TU Wien to be rejected.
Change to allow mails from outside by setting the ignore the value of SPAM level accordingly:
- Delete value (field is then empty!) - all restrictions are removed (if Block SPAM level is also empty).
- Value > 0 - Set the level according to the suggestions or other FAQ topics to reduce the amount of spam.
Enter via your personal entry in the whitepages or directly at the email options, opens an external URL in a new window and insert the values 8 for Spam-Block-Level and 10 for Spam-Ignore-Level in the line with the generic address.
The values 8/10 leave some room for possibly wrong or too strictly rated "correct" mails. You have to adjust this individually to your needs (upwards or downwards).
If an address has not been newly entered, this is usually active in mail routing within 10 minutes. In exceptional cases this can take up to 30 minutes.
For new addresses or addresses entered for the first time, you must confirm the entry using the challenge-response procedure (so that other people cannot manipulate the properties of their own addresses). After the confirmation, the setting on the mail servers is then active after the period mentioned above.
In principle, this is not possible in all cases.
The option with the option to deselect (suppress) the spam mark in the subject or subject only has an effect if a mail is personally addressed to a person or if all recipients have suppressed the subject or subject mark.
Those who filter with procmail and formail can reliably remove the mark as follows:
# Remove spam mark in subject:
* ^Subject: \[SPAM\?\]\/.*
|formail -I"Subject: $MATCH"
This is a normal behavior, because "blocking", as opposed to "ignoring", is a non-strict option, which means that in the case of an email to multiple recipients, the forwarding can happen if any other recipient has a higher or not set (=infinite) block level. Thus, the maximum of all recipient block levels is decisive.
Yes, because the block level does not always work, but the ignore level does. On the other hand, when blocking, you have the advantage that the recipient will be informed about the blocking via a bounce mail (in case a non-spammer is caught).
From this it follows that usually the following applies
- Either specify only the ignore level (the block level is implicitly set to the same value),
- or Ignore-Level > Blocklevel, so that only "heavier spam cases" are discarded without comment, but in a grey range from Block-Level to Ignore-Level, the message is rejected - if possible - with a sender notification (bounce).
Even if specifying non TU Wien addresses via the email option, opens an external URL in a new window interface is permitted, this does not have any effect if the mail has not made its way through a corresponding TU mail server. In the concrete case it is to be excluded that directly addressed GMX addresses run via the TU Wien.
The situation is somewhat different, however, if one has the forwarding to a GMX address in the whitepages and the mail was addressed to the corresponding generic address. On this way of forwarding, which leads over a TU mail server (Incoming Mailrouter), the email options come very well to the development.
Hardly. The block level dominates the ignore level, which means that if the block level is exceeded for single receivers or the block level maximum for multiple receivers, the message is "blocked" (bounce to sender). Otherwise, the message is simply discarded without comment if the spam level is higher or equal to the ignore level. The other way around the mentioned levels make more sense.
All email addresses in circulation (relevant to the TU Wien) can or should be entered in the email options, opens an external URL in a new window interface.
Sometimes "spam-loaded" role addresses (such as mailinglist@, or root@ etc.) can be protected in this way, but with the downside that they are tied to a specific person.
- In the course of the challenge-response validation, all members of a list behind it may receive the email to be confirmed!
- Various address variants, e.g. plussed users, e.g. firstname.lastname@example.org, must be listed in all (actually occurring) variants. There is no form of pattern matching or wildcards here.
- Each entry is regarded as a single address.
With the special "Ignore spam level" value of 0 (zero) a basic suppression can be forced (in particular this also applies to mails with a spam level of < 0!). This can be used for all mail addresses (including generic addresses since Dec. 2008):
- all generic forms (@tuwien.ac.at, @student.tuwien.ac.at, @alumni.tuwien.ac.at)
- Function and distribution addresses created via whitepages or TISS address book (@tuwien.ac.at)
- Other recipient addresses arriving via the mail bastion *@*.tuwien.ac.at
- Foreign domain addresses that explicitly lead to a TU Wien mail server via the mail bastion.
Note: If you want to explicitly "block" special forms of the many generic address forms, you can list the concrete address form in the email options form, opens an external URL in a new window in the section "for TU delivery addresses" and provide it with the desired, individual values, e.g. as above with ignore spam level = 0 set and thus block from external.
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