yesterday I sent an e-mail from my company e-mail account to another company account, using Zimbra webclient on my smartphone. Unfortunately it was marked as SPAM, so I got task to find out why.
Here is header of the message:
X-Spam-Flag: YES X-Spam-Score: 10.803 X-Spam-Level: ********** X-Spam-Status: Yes, score=10.803 tagged_above=-10 required=6.6 tests=[BAYES_20=-0.001, HELO_NO_DOMAIN=0.001, RCVD_IN_BL_SPAMCOP_NET=3, RCVD_IN_BRBL_LASTEXT=3, RCVD_IN_PSBL=2.7, RCVD_IN_RP_RNBL=1.31, RDNS_NONE=0.793] autolearn=no
Every "significant" rule is connected with presence on particular blacklist, as SpamAssassin's wiki informs. I have checked all of them and our company server is not listed anywhere.
About rDNS - we have it.
Today I've tried to reproduce problem. I sent similar mail from my smartphone and I below is what I got:
X-Spam-Flag: NO X-Spam-Score: 3.294 X-Spam-Level: *** X-Spam-Status: No, score=3.294 tagged_above=-10 required=6.6 tests=[BAYES_05=-0.5, HELO_NO_DOMAIN=0.001, RCVD_IN_BRBL_LASTEXT=3, RDNS_NONE=0.793] autolearn=no
Only two rules stayed: rDNS and Barracuda Reputation Block List.
As I mentioned: rDNS is set up correctly. Query BRBL again returns:
Host *.b.barracudacentral.org not found: 3(NXDOMAIN)
which is good result, as far as I read.
When sending e-mail from webclient on PC or from Thunderbird, SPAM header looks like:
X-Spam-Flag: NO X-Spam-Score: -2.9 X-Spam-Level: X-Spam-Status: No, score=-2.9 tagged_above=-10 required=6.6 tests=[ALL_TRUSTED=-1, BAYES_00=-1.9] autolearn=ham
Our configuration: Zimbra 7.1 (yes, I know it's old, it'll be migrated soon) on Ubuntu.
I can't figure it out. If you need more information, I'll provide them.