E-Mail-Loop
E -mail Loop is a borrowed from the English name for a loop ( engl.: loop ) in an e -mail will be forwarded endless ( infinite loop ).
E -mail Loops occur, for example, if two email addresses are passed to each other.
Example:
- [email protected] - forwarded - to → [email protected]
- [email protected] - forwarded - to → [email protected]
If now an e -mail sent to or [email protected] [email protected], created an e -mail loop, in which the e -mail is endlessly between the two addresses back and forth - if further action this is not prevent.
These e -mail loops are not restricted to two addresses, but can theoretically be any number of redirects extend. Then the loop for any of the workers involved is obvious. Are particularly problematic e- mail loops, if one of the addresses involved will be forwarded to a mailing list or e -mail distribution.
Detection of email loops
In general, let E -mail Loops on striking gestiegenem e -mail traffic (volume and number ) or unusually high utilization of a mail server to recognize. Is the e- mail loop an e -mail distribution list containing the beneficiaries participating in the endless loop notice the problem usually pretty fast to very many of the same, arriving at short intervals e-mails.
Countermeasures
Most mail servers have the means to monitor e- mail loops can be detected and interrupted. So usually an e- mail will not be forwarded if it has previously been passed over a certain number of mail servers (indicated by the Received headers ), or if the receiving mail server recognizes that he has previously delivered this message to the same recipient.
The fact that it comes to e- mail loops, which are not automatically interrupted, is mainly due to inadequate configuration of the mail server or software that either do not or not sufficiently taken into account the risk of e- mail loops. Affected are often autoresponder that the sender identify a message (eg absence wg. Holiday ), although the received message itself an autoreply is already ( then maintain two auto-responder ) or mailing lists, where the Received header are automatically removed and so an automatic loop detection (see above) make it impossible.