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61

The whole idea behind the MX record is to specify a host or hosts which can accept mail for a domain. As specified in RFC 1035, the MX record contains a domain name. It must therefore point to a host which itself can be resolved in the DNS. An IP address could not be used as it would be interpreted as an unqualified domain name, which cannot be resolved. ...


13

DNS as a protocol has some different types of values, these are not interchangable. It's important to note that DNS is a binary protocol with strict mappings between the type of record and the type of data that such a record holds. For example: An A record holds an IPv4 address (4 bytes of data, fixed length). An AAAArecord holds an IPv6 address (16 bytes ...


8

CentOS 6 comes with Postfix as default mail server and you can see it running (tcp :25 1186/master). Try to stop Postfix (service postfix stop) and then start sendmail (service sendmail start).


5

I'll throw this out as a guess. Course, I'm home with the flu so maybe I'm loopy. RFC 974 states: The first step for the mailer at LOCAL is to issue a query for MX RRs for REMOTE. It is strongly urged that this step be taken every time a mailer attempts to send the message. The hope is that changes in the domain database will rapidly ...


4

The helo name of the attacker is invalid (ylmf-pc) because it's neither a FQDN, nor resolvable via DNS, so you can easily get rid of it earlier, by blocking him after the invalid EHLO is sent. To do this with postfix, for example, do: smtpd_helo_restrictions = permit_mynetworks, check_helo_access reject_invalid_helo_hostname, reject_non_fqdn_helo_hostname, ...


4

Your smtpd_relay_restrictions should prevent that anyone can connect to my server and use it as an open relay for spam. The value of mynetworks does not determine if others can email you. 127.0.0.0/8 is a correct value 0.0.0.0/0 is not. What determines if email for your account username@example.com is accepted is determined by the settings that inform ...


4

It doesn't have to return the top level domain. The forward and reverse DNS should match i.e. nslookup x.x.x.x should return some.random.subdaomains.mydomain.com and nslookup some.random.subdaomains.mydomain.com should return x.x.x.x This is done as sometimes the receiving mail server will perform this check in an attempt to detect if the mail is spam. ...


4

To always permit realying on mail.example.com by web.example.com, you can add web.example.com to your trusted network: mynetworks = 127.0.0.1/32 [your IPv4 and IPV6 addresses] [IP of web.example.com] Alternatively you can use smtpd_client_restrictions: smtpd_client_restrictions = permit_mynetworks, check_client_access hash:/etc/postfix/maps/client_access ...


3

Form my understanding I could use PHP mail() function or even Swift Mailer's Swift_SendmailTransport class and deliver the messages directly to Postfix queue. That's true But if so, how can we ensure DKIM? Will changing the "FROM" header to the email accounts on the local server be enough? You doesn't specify your DKIM signer, so I assume that you ...


3

Most MTAs will go to nearly any end to avoid dropping a message on the floor. Typically a bounce will be generated (either by the receiving MTA, or, for better-behaved MTAs, the receiving MTA will refuse with a 5xx fatal error code and the sending MTA will convert the outbound message into a bounce). If that bounce is itself undeliverable, the MTA holding ...


3

SMTP protocol is used to accept and relay email, but is not used for email reading. So - when you authenticate to SMTP, server can accept your emails and forward them to other MX servers, but cannot let you download existing mails from the server. If you want to read emails on your mobile phone or your PC you will need to use IMAP or POP3 protocol. To ...


3

In dovecot -n output, looks like you have enabled 'ssl-enforcing' mode ssl = required The result is here the dovecot output when telnet 127.0.0.1 143 * OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE STARTTLS LOGINDISABLED] Dovecot ready. With 'ssl-enforcing' mode, IMAP client (javamail code) must issuing STARTTLS command ...


3

FYI, 454 4.7.1 <someemail@example.com: Relay access denied; was the result of defer_unauth_destination. It's slightly different with reject_unauth_destination, with reject means permanent error with code 550 and defer means temporary error with code 450. But wait..., I don't have any parameter that use defer_unauth_destination. Where does the weird ...


3

That idiosyncratic and invalid EHLO argument "ylmf-pc" is a known fingerprint of a widespread spamming botnet known as "PushDo" (and sometimes alternatively "Cutwail"). As shown in your transcript, it is mostly trying password guessing to authenticate and send mail through your server. Keeping it from sending spam to or through your server is easy, because ...


3

Disclaimer: this answer doesn't contain the solution about how to make postfix bcc email twice. I'm just decipher the content of your maillog line. Postfix part pre-content_filter Feb 3 13:30:25 email1mail postfix/submission/smtpd[3319]: connect from somewhere[xxx.xxx.xxx.xxx] Feb 3 13:30:25 email1mail postfix/submission/smtpd[3319]: 47F943003E: ...


2

Some email servers (like exim) specifically do not allow sending to MX records that point to a pure IP address, so you're required to use a FQDN for it instead to be compliant. This is because most servers expect the MX record to contain a hostname, not an IP (that's what A records are for). Edit: To elaborate, in DNS each record has strict requirements for ...


2

<bot>Converting comment to CW</bot> Looks like OpenDKIM was mistakenly looking private key in another directory. Running this command cp /etc/opendkim/keys/default.private /etc/opendkim/default.private magically fixed it o.0. I'm not sure why this is happened


2

I ran into something similar recently. In my case, scanning the logs I noticed some memory allocation errors and this, together with some hints from pages, suggested to me that the node didn't have enough RAM to operate properly. I've subsequently added 1GB of swap which seems to have helped. So I'd tentatively suggest it's a low memory condition -- add ...


2

Could it be that the sending servers can't connect to the primary MX and are delivering to the secondary MX as a result? If so, removing the secondary MX records will force the sending servers to queue the email for later retries to the primary MX


2

Firstly, so long as you have OpenDKIM specified in non_smptd_milters as well as smptd_milters in Postfix's main.cf, outgoing mail sent through PHP mail() should still be signed. The Received headers are not signed by default, and nothing much else should have been rewritten by cleanup. If you want an alternative method, you could DKIM sign using Amavis and ...


2

In the Account Editor in MDaemon you can configure users to access via POP, IMAP and the WorldClient only from LAN IP's. The settings are under Mail Services and Web Services.


2

Choose a domain name for your mail server. The MX record should point to the FQDN (Fully Qualified Dommain Name) of the mail server, shuch as smtp.example.com. All domains should use this FQDN in their MX. Use a priority higher than 1 so that you can add servers with both higher and lower priority. Something like: example.com. mx 10 ...


1

An MX record for a domain can "point" to any host, so having them all "point" to the same server is fine. As for the preference, you can set it to whatever you like. If you add servers in the future you can add them with a higher or lower preference, dependent upon your needs.


1

Your email domain. And you should publish public key via dns DKIM provides a method for validating a domain name identity that is associated with a message through cryptographic authentication - so,in simple words that message from "user@example.com" really send (and wasn't modified in process) by example.com mail server. So - yes, you should have separate ...


1

How sure are you that there isn't something going on with your server? There's a significant chance that it is actually your server that is the problem Regardless, there's nothing we can really recommend other than to perform typical troubleshooting steps such as collecting logs, packet captures, etc., then looking through them with a fine-toothed comb so ...


1

the setting of smtpd_relay_restrictions you have is correct except that you defined your mynetworks wide open (shown below from your main.cf) mynetworks = 0.0.0.0/0 Just remove mynetworks; the default value should restrict relay access. For example, mine comes out as shown below with default. postconf -d |grep mynetworks mynetworks = 127.0.0.0/8 ...


1

Found this solution: add this on /etc/dovecot/conf.d/20-lmtp.conf: protocol lmtp { postmaster_address = mysql:/etc/postfix/mysql-virtual-mailbox-maps.cf # required mail_plugins = quota } probably this was: protocol lmtp { # Space separated list of plugins to load (default is global mail_plugins). #mail_plugins = $mail_plugins }


1

start with the document /usr/share/doc/exim4/README.Debian.gz section 2.1 you want one of these settings: (as root do dpkg-reconfigure exim4-config) 2.1.1.1.1. internet site; mail is sent and received directly using SMTP 2.1.1.1.2. mail sent by smarthost; received via SMTP or fetchmail 2.1.1.1.3. mail sent by smarthost; no local mail if you chose ...


1

IN RFC 1025 MX records only point to a RR (resource record) of an A Record or a CNAME. So the mail server sending the mail asks for the RR of an MX record, the mx record lists A records of servers, the mail server does a forward lookup to get an A record and then forwards the mail via smtp to the service host listed as a mail server 'willing' to receive ...


1

<bot>Converting comment to CW</bot> Looks like postfix wants to connect to your custom service port 7777, something like check_policy_server. Unfortunately for whatever reason the service doesn't run. Also according to this log warning: do not list domain 89ninetymailserver.com in BOTH mydestination and virtual_mailbox_domains you have ...



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