1 Topic by waihongleong7

  • waihongleong7
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Topic: How to block scam email

Hi support.

We have been receiving quite a number of scam email lately.
May I know is there a way to block these email?
Thanks.

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2 Reply by ZhangHuangbin

  • ZhangHuangbin
  • ZhangHuangbin
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Re: How to block scam email

Cannot help without details.
Check Postfix log file (/var/log/maillog), Amavisd will log matched SpamAssassin rules, you can consider increase its score to tag them as spams.

3 Reply by wh.leong

  • wh.leong
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  • Registered: 2019-10-31
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Re: How to block scam email

Hi Huangbin.

May I check with you regarding spam email and scam email?
I'm understand that we can use spamassassins rules to control the number of spam email.

Is it possible to individually block the spam email as the spam assassins is a global settings and will affect all the users if we change the values globally? We also do not want the users to receive these spam emails while we are able to check if the email is being quarantined or blocked.

Also, is it possible to tag any email that we received from external party as an external mail, for example, users in XYZ company (xyz.com) will receive email from external party (e.g. abc.com) with subject title {External} attached in front to warn the staff that the email is from an external source and will be careful in opening the email?

Thanks.

4 Reply by waihongleong7

  • waihongleong7
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Re: How to block scam email

ZhangHuangbin wrote:

Cannot help without details.
Check Postfix log file (/var/log/maillog), Amavisd will log matched SpamAssassin rules, you can consider increase its score to tag them as spams.

Hi Huangbin.

Thanks.
May I know if it is possible to individually block the spam email as the spam assassins is a global settings and will affect all the users?
Thanks.

5 Reply by waihongleong7

  • waihongleong7
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Re: How to block scam email

Hi Huangbin.

Also, please advise if it is possible to enable a tag on all the email received from external party as [External] and how do we configure this?
Thanks.

6 Reply by ZhangHuangbin

  • ZhangHuangbin
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Re: How to block scam email

SpamAssassin score rules in /etc/mail/spamassassin/local.cf are applied globally.

7 Reply by wh.leong

  • wh.leong
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Re: How to block scam email

wh.leong wrote:

Hi Huangbin.

May I check with you regarding spam email and scam email?
I'm understand that we can use spamassassins rules to control the number of spam email.

Is it possible to individually block the spam email as the spam assassins is a global settings and will affect all the users if we change the values globally? We also do not want the users to receive these spam emails while we are able to check if the email is being quarantined or blocked.

Also, is it possible to tag any email that we received from external party as an external mail, for example, users in XYZ company (xyz.com) will receive email from external party (e.g. abc.com) with subject title {External} attached in front to warn the staff that the email is from an external source and will be careful in opening the email?

Thanks.

Hi Huangbin.

Thanks for the advise.
May I know if it is possible to tag any email with the subject header [External] for all email that is coming from external sources?
Thanks.

8 Reply by ZhangHuangbin

  • ZhangHuangbin
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Re: How to block scam email

wh.leong wrote:

May I know if it is possible to tag any email with the subject header [External] for all email that is coming from external sources?

I didn't try it before, but it should be possible.

Port 25 is used for incoming emails, so you may tune /etc/postfix/master.cf and use additional header_check rules to append some text in header.

9 Reply by wh.leong

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Re: How to block scam email

Hi Huangbin.

Thanks for the advise.
May I know which portion should I add in the additional header_check rules for /etc/postfix/master.cf rules?
Thanks.

10 Reply by elmau

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Re: How to block scam email

wh.leong wrote:

Hi Huangbin.

Thanks for the advise.
May I know which portion should I add in the additional header_check rules for /etc/postfix/master.cf rules?
Thanks.


For example:

sudo vim /etc/postfix/header_checks

/^Subject: =?big5?/     REJECT Chinese encoding not accepted by this server
/^Subject:.*your messages failed.*/     REJECT Sorry, your message is probably spam