Greylisting is a technique for fighting spam by initially rejecting emails.

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How does postgrey handle changing FQDNs?

Let's say I receive emails from the following clients: mail2.dx300.mail.net mail4.dx121.mail.net mail5.dx121.mail.net Even though these are all from the same service (e.g. LinkedIn or MailChimp), ...
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1answer
73 views

Use greylisting only if SPF fails

I have noticed that more and more people using the DNS based SPF records and I want to enhance my spam filter. I am using SPF and greylisting after each other and my idea would be to use only ...
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1answer
37 views

Evaluation of mail server configuration

I have a mail server configured to use DNS real-time blacklists (DNSRBLs), e.g. zen.spamhaus.org, to determine whether delivered email is spam or not. I would like to evaluate my mail server's ...
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3answers
239 views

How long are the default times for greylisting? [closed]

In Wikipedia it sais: A mail transfer agent (MTA) using greylisting will "temporarily reject" any email from a sender it does not recognize. If the mail is legitimate the originating server ...
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1answer
278 views

Configure postfix to delivers faster when a mail got greylisted

Where do I configure the time postfix waits until it tries to resend an email from the queue if an email was grey-listed on the recipient side? I would like to configure it, so my server tries to ...
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1answer
836 views

Postgrey not greylisting incoming emails

I migrated my server to a new provider and have postfix & everything else back up and running, but am not getting incoming mails greylisted anymore when I have postgrey running. I was on CentOS ...
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4answers
4k views

Is greylisting still an efficient method for preventing spam?

I've used greylisting on my servers for many years, but I don't know how effective it is nowadays. Is it still good for fighting spam in 2012? Or is the typical spammer MTA capable of resending ...
2
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1answer
558 views

Some emails are being delivered, some returned

I have my own VPS where a site is running (control panel: directadmin). When I send mails, some are being delivered (hotmail, gmail, me@somedomain.com ,...), others are not (me@somedomain2.com), ...
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1answer
223 views

exim greylisting non-auth SMTP mail?

I have smtp auth set up on my exim4 Dqueeze server so that only auth'ed clients can use it as a mail relay. I believe this is working, e.g. thunderbird (w/out password) reports that I am "not yet ...
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3answers
304 views

What's the ideal greylist scheme with multiple MX in different locations?

We currently have two MX servers in the same physical rack, they are sharing the same greylist database, and everything seems to work well. The two MX have different priorities and they are on two ...
1
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1answer
382 views

Postfix policyd dual usage setup - greylisting and quotas

On our server we are using policyd 1.x together with Postfix 2.1.5 for greylisting and enforcing incoming quotas from unauthorized users (ie. mail for our domains). For this, I have set up Postfix ...
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1answer
92 views

Greylisting with two mail servers

I have two mail servers and would like to make use of greylisting, but am not sure if this simply works with two servers. E.g. when a sender gets greylisted and uses the second server for the second ...
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3answers
594 views

GeoIP based greylisting with Exim?

I have been using Sendmail together with milter-greylist for many years at several sites. milter-greylist has support for defining greylisting rules based on GeoIP database lookups. This is very ...
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2answers
958 views

avoid greylisting with postfix

I have an email marketing app, so we have a great volume of mails to send and sometimes a great volume to the same MX. Depending the MX configuration we enter in a greylist and the server told us (in ...
1
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4answers
726 views

How long does it take for a server to get 'off greylisting'

I asked a question regarding email delays a few months ago, and I think I found a workaround. I changed our email from "noreply@site.com" to "someone@gmail.com", and it seems to work instantly ...
0
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1answer
564 views

Exim log and send all mail for a given domain through another server

I administer a handful of shared web hosting servers. Recently, Yahoo has been deprioritizing/greylising all email sent from these servers. I am getting the dereaded 421 4.7.0 [TS02] Messages from ...
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7answers
2k views

Does SMTP greylisting a) stop much spam and b) stop much legitimate mail?

I've just set up an SMTP server on a relatively little used domain using Postfix and enabled greylisting with SQLGrey. So far it seems to be working OK, and while there's the slight irritation of ...