User Tools

Site Tools


greylisting

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
greylisting [2006/12/08 12:42]
adam Added config placement decision
greylisting [2016/11/25 22:38] (current)
Line 30: Line 30:
 Placement of this snippet in the config is important. I place it in my ACL section, beneath the RDNSBL and ClamAV sample sections, so that bad senders detectable by other means still have to get through greylisting when they become delisted or send non-viral email. Other people put this config before other checks, the decision is yours. Placement of this snippet in the config is important. I place it in my ACL section, beneath the RDNSBL and ClamAV sample sections, so that bad senders detectable by other means still have to get through greylisting when they become delisted or send non-viral email. Other people put this config before other checks, the decision is yours.
  
-The commented line was used in the Debian greylistd docs (possibly standard with greylistd) in /​usr/​share.doc/​greylistd/​examples/​exim4-acl-example.txt,​ but this ACL didn't apply to the Vexim configuration. There is additional config available elsewhere which shows how to catch mails without an envelope sender. References required.+The commented line was used in the Debian greylistd docs (possibly standard with greylistd) in /​usr/​share.doc/​greylistd/​examples/​exim4-acl-example.txt,​ but this ACL didn't apply to the Vexim configuration. There is additional config available elsewhere which shows how to catch mails without an envelope sender ​but I never found it. References required.
  
-Note that greylisting also has some disadvantages:​ emails are always delayed and some mail servers do not properly ​retry after the first delivery attempt, so emails from these servers are never delivered. Blueyonder and some servers at yahoo.com and ebay.com are known for this. It is therefore important to have a good white list.+Note that greylisting also has some disadvantages:​ emails are always delayed ​from an unknown sender ​and some (stupid) ​mail servers do not retry after the first delivery attempt, so emails from these servers are never delivered. Blueyonder ​aka Virgin Media and some servers at yahoo.com and ebay.com are known for this. It is therefore important to have a good white list. Be sure to keep an eye on your logs for mails from legitimate senders that never retry and whitelist them. 
 + 
 +You can set your greylisting retryMin down to 10 seconds, you might get a slight increase in spam and lose the benefit that spammy senders will normally be blacklisted in RBLs within an hour, but you don't have to wait so long for real mail to get through if time is sensitive
  
 Other greylisting implementations:​ Other greylisting implementations:​
greylisting.txt · Last modified: 2016/11/25 22:38 (external edit)