Re: 5XX vs 4XX

2019-11-02 Thread Wietse Venema
John Schmerold: > I have a few email addresses that were valid 15 years ago, but they have > been invalid for 5+ years, we are rejecting them with a 450 message, my > thought is "Let's tie up this spammer's computer just a little bit" > > Good idea? Bad idea? Effective? Ineffective? I think it

Re: Dictionary attacks

2019-11-02 Thread Wietse Venema
John Schmerold: > What is the best way to protect against dictionary attacks in Postfix? Reportedly, fail2ban (no first-hand experience, because I have no SASL clients). Wietse

Re: Warning on Connection time

2019-11-02 Thread John Schmerold
On 11/2/2019 3:20 PM, John Schmerold wrote: https://mxtoolbox.com/diagnostic.aspx reported a six second connection time, with total transaction time of nearly 9 seconds, so I dug into the issue. I suspect I have rbl issues (perhaps too many): postscreen_dnsbl_sites =

Re: Warning on Connection time

2019-11-02 Thread Bill Cole
On 2 Nov 2019, at 16:20, John Schmerold wrote: https://mxtoolbox.com/diagnostic.aspx reported a six second connection time, Feature, not bug. Postscreen's greeting pause puts 6 seconds between the lines of the initial greeting for clients that are not cached. e.g.: Logs say: Nov  2

Re: Warning on Connection time

2019-11-02 Thread Matus UHLAR - fantomas
On 02.11.19 15:20, John Schmerold wrote: https://mxtoolbox.com/diagnostic.aspx reported a six second connection time, with total transaction time of nearly 9 seconds, so I dug into the issue. I suspect I have rbl issues (perhaps too many): postscreen_dnsbl_sites =

Warning on Connection time

2019-11-02 Thread John Schmerold
https://mxtoolbox.com/diagnostic.aspx reported a six second connection time, with total transaction time of nearly 9 seconds, so I dug into the issue. I suspect I have rbl issues (perhaps too many): postscreen_dnsbl_sites =

Re: block 'new style' TLDs ?

2019-11-02 Thread Kevin A. McGrail
On 11/2/2019 2:38 PM, John Schmerold wrote: > On 10/24/2019 12:32 AM, @lbutlr wrote: >> On 23 Oct 2019, at 15:20, lists wrote: >>> /\.asia$/ 510 Denied: Unacceptable TLD .asia >> [Long list… removed] >> >> smtpd_helo_restrictions = reject_invalid_helo_hostname >> check_helo_access

Re: 5XX vs 4XX

2019-11-02 Thread Patrick Proniewski
Hi > On 02 nov. 2019, at 19:44, John Schmerold wrote: > > I have a few email addresses that were valid 15 years ago, but they have been > invalid for 5+ years, we are rejecting them with a 450 message, my thought is > "Let's tie up this spammer's computer just a little bit" > > Good idea?

5XX vs 4XX

2019-11-02 Thread John Schmerold
I have a few email addresses that were valid 15 years ago, but they have been invalid for 5+ years, we are rejecting them with a 450 message, my thought is "Let's tie up this spammer's computer just a little bit" Good idea? Bad idea? Effective? Ineffective? -- John Schmerold Katy Computer

Re: block 'new style' TLDs ?

2019-11-02 Thread John Schmerold
On 10/24/2019 12:32 AM, @lbutlr wrote: On 23 Oct 2019, at 15:20, lists wrote: /\.asia$/ 510 Denied: Unacceptable TLD .asia [Long list… removed] smtpd_helo_restrictions = reject_invalid_helo_hostname check_helo_access pcre:/etc/postfix/helo_checks.pcre permit

Re: block 'new style' TLDs ?

2019-11-02 Thread John Schmerold
On 10/24/2019 4:46 AM, Jaroslaw Rafa wrote: Dnia 23.10.2019 o godz. 23:32:44 @lbutlr pisze: /etc/postfix/helo_checks.pcre: /.*\.(com|net|org|edu|gov|ca|mx|de|dk|fi|fr|uk|us|tv|info|biz|eu|es|il|it|nl|name|jp|host|au|nz|ch|tv)$/ DUNNO /.*\.*$/ 550 Mail to or from this TLD is not allowed And

Dictionary attacks

2019-11-02 Thread John Schmerold
What is the best way to protect against dictionary attacks in Postfix? Exim has a rcpt_fail_count variable I use to drop connections with the attacker:   drop  condition = ${if > {${eval:$rcpt_fail_count}}{3}{yes}{no}}     log_message    = Dictionary Attack Rejected (Began blocking after