Difference between revisions of "User:Woozle/2016/02/15/Postfix bounce-spam"
Jump to navigation
Jump to search
(note about SPF) |
(tcpdump) |
||
| Line 6: | Line 6: | ||
# [[/2016/02/14/21:32:58]] | # [[/2016/02/14/21:32:58]] | ||
# [[/2016/02/14/21:33:07]] (received right after #2; part of a sequence of 4 addressed to coinstar6116) | # [[/2016/02/14/21:33:07]] (received right after #2; part of a sequence of 4 addressed to coinstar6116) | ||
| + | |||
| + | Possible evidence: | ||
| + | * [[/tcpdump 1]] | ||
Some points of note: | Some points of note: | ||
Revision as of 16:37, 15 February 2016
Explanation / discussion: Google+
Sample emails:
- /2016/02/14/19:59:08
- /2016/02/14/21:32:58
- /2016/02/14/21:33:07 (received right after #2; part of a sequence of 4 addressed to coinstar6116)
Possible evidence:
Some points of note:
- Our mail server is cloud2.hypertwins.net.
- ownedbycats.org is one of the domains hosted on that server. (A complete list, from memory: hypertwins.com/net/org, ownedbycats.com/net/org, vbz.net)
- ownedbycats.org and hypertwins.org are both set for catch-all (i.e. will accept email to [any address]@[domain]).
- Both of those .org domains are configured with an SPF host record to prevent messages with those domains being sent from anywhere except cloud2.
- Yes, we could probably eliminate most or all of the spam by disabling catch-all (i.e. only accepting email to certain addresses) -- but if the server is being abused to send spam, turning off catch-all wouldn't necessarily prevent that, and the abuse would become invisible to us.