Re: Sending to a nolisting-enabled host
- On Mon, Oct 30, 2006 at 01:49:10PM +0100, emailteszt wrote:
> Oct 30 13:38:01 mail MailScanner: Requeue: 9B94C49365.737C7 to D2D3B4934AThis software is known to not work reliably with Postfix.
> Oct 30 13:38:01 mail postfix/qmgr: D2D3B4934A: from=<something@somehost>, size=1011, nrcpt=1 (queue active)sx.mail.vietnamfree.com has address 184.108.40.206
> Oct 30 13:38:31 mail postfix/smtp: D2D3B4934A: host sx.mail.vietnamfree.com[220.127.116.11] refused to talk to me: 421 Server not available
> Oct 30 13:39:01 mail postfix/smtp: D2D3B4934A: to=<valami@...&>, relay=sx.mail.vietnamfree.com[18.104.22.168], delay=66, status=deferred (host sx.mail.vietnamfree.com[22.214.171.124] refused to talk to me: 421 Server not available)
> The server's MX records:
> host -t mx tvn.hu
> tvn.hu mail is handled by 6 mail20.vietnamfree.com.
> tvn.hu mail is handled by 6 mail25.vietnamfree.com.
> tvn.hu mail is handled by 6 mail30.vietnamfree.com.
> tvn.hu mail is handled by 10 mail40.vietnamfree.com.
> tvn.hu mail is handled by 5 sx.mail.vietnamfree.com.
> The sx.mail.vietnamfree.com is the non-working MX record. The second ones do work, but our smtp isn't using them.
sx.mail.vietnamfree.com has address 126.96.36.199
sx.mail.vietnamfree.com has address 188.8.131.52
sx.mail.vietnamfree.com has address 184.108.40.206
The best-mx host has 4 IP addresses. Postfix will try these addresses before
using any of the backup MX hosts.
With Postfix 2.3, at most 5 addresses are tried by default, so after
failing 4 times on the primary MX, there will be one more connection
attempt with one of the preference 6 hosts. At most two delivery
attempts are made with hosts that don't refuse to talk SMTP (220
banner and 250 EHLO/HELO).
smtp_mx_address_limit = 5
smtp_mx_session_limit = 2
With Postfix 2.1/2.2 (and perhaps 2.0), there is no limit on the
number of addresses to connect to, but when the server issues a 220
banner, and then a 4XX/5XX helo, this counts against the 2 session
limit, rather than against the (default unlimited) connection
limit. Servers with a 4XX/5XX banner are logged as "connect to
<name>[<ip>]: server refused to talk to me: <banner>", while servers
with a 4XX/5XX EHLO/HELO response are logged as "host <name>[<ip>]
refused to talk to me: <HELO response>"
smtp_mx_address_limit = 0
smtp_mx_session_limit = 2
Given your logs, we see that you are running Postfix 2.1 or 2.2 and the
server is turning away connections during EHLO/HELO rather than with a
The solution is to upgrade to Postfix 2.3 and perhaps set a somewhat
smtp_mx_address_limit = 10
though in your case 5 is just enough to get past the non-cooperative host.
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