1 Topic by AndyInNYC

  • AndyInNYC
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  • Registered: 2017-08-18
  • Posts: 145

Topic: Greylisting - does the system 'learn' when it gets email?

==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.7
- Linux/BSD distribution name and version: Ubuntu 16.04
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Apache
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I have a friend using an email account on my system and he's concerned with delivery time.  I used my ComcCast account to send a test message and the system 'rejects' it and asks that it be resent (this is by design).

ComCast seems to take it's sweet time in re-sending an email (ComCast is just as an example).  My friend doesn't really like the delay.

Is there a way, other than whitelisting the world as an admin that the system can accept emails in the future once an email has been received or replied to without the delay?

I recognize his irritation since email is now virtually instantaneous.


Andrew

----

Spider Email Archiver: On-Premises, lightweight email archiving software developed by iRedMail team. Supports Amazon S3 compatible storage and custom branding.

2 Reply by swejun

  • swejun
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  • Registered: 2017-07-26
  • Posts: 84

Re: Greylisting - does the system 'learn' when it gets email?

Hi,
have a look at  http://www.iredmail.org/docs/manage.iredapd.html
under the "Greylisting" section.
1) you can disable greylisting totaly ( bad idea, better to tune the settings)
2) check/manipulate white listing of domain and email addresses

For you questions: Yes Greylisting is learning/ remembering. (configurable values in settings.py)
- 15 minutes is the retry timeout for clients, a retry must wait 15 minutes
- 30 days is the time period a sender/recipient/clent (=triplet) is remebered. Auto whitelist 30 days
- 1 day is the timout for "remebering" an attempt but no retry.

Check existing white listing
#   cd /opt/iredapd/tools
#  python  greylisting_admin.py --list-whitelist-domains
#   python  greylisting_admin.py --list-whitelists
#  python  greylisting_admin.py --list

  * Disable greylisting for emails which are sent
      from anyone to local mail user `user@example.com`:
        # python greylisting_admin.py --disable --to 'user@example.com'

   * Disable greylisting for emails which are sent
      from `gmail.com` to local mail user `user@example.com`:
        # python greylisting_admin.py --disable --from '@gmail.com' --to 'user@example.com'
/ Regards

3 Reply by carlkyo

  • carlkyo
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  • Registered: 2010-06-30
  • Posts: 24

Re: Greylisting - does the system 'learn' when it gets email?

hi
I have been using iRedmail for many year
I find it so difficult to tune Greylisting
it always make the mail slow down( half hour delay avg)
I finally turn it off
thanks

4 Reply by swejun

  • swejun
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  • Registered: 2017-07-26
  • Posts: 84

Re: Greylisting - does the system 'learn' when it gets email?

I have used greylisting for many years, on various systems and for various organisations I have been involved with
At my current position, I have statistics for the last 14 months.
With greylisting active, 85% of incomming e-mails are bounced, most of them are never retried, i.e. an incoming email in the form <sender helo: spamhost>  <from: spammer1> to: <existing user 1>  is greylisted. The next mail from the same sending host is <from: spammer2> , so this e-mail is also greylisted.

If I turn of greylisting, the number of e-mails caught in spam/content filter explodes, and the number of Quarantine items grows from 5 to 100 per day (this is a fairly smal organisation)

The feature in iredmail  policy server IredAPD, using SPF records to whiitelist sending hosts for a valid domain is excelent.
( = whitelist all legitimate smtp sending hosts at google, hotmail, facebook  etc with a single command)
I also add to white list domains our business partners and other domains of importance. For users specifically asking for No Greylisting, it's easy to whitelist a single recipient.

I have also worked with systems using postfix/mailscanner/postgrey. Mailscanner keeps a daily updated whitelist of sending hosts/domains. It doesnt come with SPF validation out-of-the-box.
So: all in all, I would say that greylisting is one of the best methods available for keeping spam out of the mail system.

PS: Add SPF, Dkim and DMARC records for you mail domain, it will help other systems whitelist Your send mail, and blacklist spam using your domain name as a faked sender.