SMTP is the Simple Mail Transfer Protocol, the most recent standard of which is defined in RFC 5321. It's the Internet standard for sending and receiving email.

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Mail queue retry interval practices

I'm configuring a custom made mail queue. The thing is there can be errors sending mail. Normally, one won't know the reason why the mail didn't reach it's destination. So the most simplistic solution ...
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3answers
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Mailbox unavailable, client does not have permissions to send as this sender - only the first time

Our users can send emails from our ASP.NET Web application on the click of a button. In our testing environment, there is a strange thing going on. The first time the application tries to send the ...
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125 views

Is Exchange 2010 compliant with RFC 3848

I have looked up Exchange 2010 Support for RFC Standards but do not see RFC 3848 amongst the supported standards. I do see RFC 4954 listed, which 'recommends use of RFC 3848 transmission types', ...
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913 views

saslauthd multi instance for postfix smtp authentication

I have mail server Postfix+Saslauth. I configure multiple instance for Postfix: postfix postfix-out and two instances for saslauth: saslauthd saslauthd-out Setting saslauthd is ...
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Why Outlook, Hotmail and Live return 250 Mail queued for delivery, but they never deliver it? [duplicate]

Ok, i've been seeing this the last week, tought it could be gone in a few days by itself, since i wasn't blacklisted and my DNS entries are all ok, but when i try to send e-mails to some user at ...
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614 views

receiving mail during Exchange maintenance?

I was part of a small company, and sometimes we had to bring down our Exchange server to perform maintenance. The majority of mail during the downtime would get redelivered in a timely manner, but ...
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In SMTP, how does one choose between “Accept than Bounce” vs “Bounce at the edge”?

There seems to be a variety of implementations of SMTP that either immediately reject a message, and others that do an accept, then bounce the message. Operationally, the accept-than-bounce is a ...
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640 views

Why is my port 25 so active?

Using netstat -na I notice that I have a lot of connections like tcp 0 0 XXX.XXX.XXX.XXX:25 YYY.YYY.YYY.YYY:13933 ESTABLISHED tcp 0 0 XXX.XXX.XXX.XXX:25 ZZZ....
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With regard to anti-spam practices, what exactly does a typical reverse DNS check look for?

My understanding is that a typical reverse DNS lookup will compare the SMTP hostname (provided in the EHLO/HELO command) of an incoming connection and verify that it matches the PTR record for the ...
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What's the difference between postfix/smtp and postfix/smtpd

A bit confused when reading through the logs of my smtp/mail server, I'm turning this questions to you guys. In the maillog files I'm seeing entries for postfix/smtp as well as postfix/smtpd. I can ...
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Forcing smtp outgoing mail encryption on postfix

anyone knows how to tell postfix to encrypt outgoing mail? I have configured it to use encryption on reception, but I´m unnable to do it with the out mail. This is my main.cf file: ...
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How to copy outgoing messages on sendmail

I've searched the serverfault and Google, but did not find anything related to my question yet. So, I have a customer that wants to read all emails sent by his employees. I've configured a VPS with ...
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3answers
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Anyone have a Powershell script to look up the MX record for a domain?

I want to check to see if the email addresses in my contact management system are valid and the best way I can think to do this is to get the MX record for their domain, then open an SMTP connection ...
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2answers
97 views

Spam addressed to a sender but received by everyone else

Spam's been getting through Postini lately that's addressed to a recipient (bob@example.com) in the To: field and in the headers. While this isn't that strange -- we've had spam get through before -- ...
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4answers
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SMTP relay through GMail overrides “from:” address with “[me]@gmail.com”

I've been trying to figure out if this is a new "feature" or if there is an issue with my configuration. I'm using Ubuntu 10.04 Desktop with Postfix as MTA. My smtp (as opposed to smtpd) ...
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5answers
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How do I configure reverse DNS for a SMTP server [duplicate]

We use iis 6 to send out emails for our website but some email addresses bouce backs. It only appears to be 2 addresses. There is at least 100 different email addresses sent to at the same time as ...
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1answer
10k views

Question on SendMail daemon actions when load average is too high

My sendmail server started rejecting connections because load average was too high (due to a spam issue that has since been resolved). Error was: sendmail[13400]: rejecting connections on daemon MTA:...
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3answers
543 views

Foreign mail server returns “502 Command not implemented.”

I am using Postfix to communicate with foreign server and send a mail. Every time when I try send mail using Postfix, I get this error: (host mx2.seznam.cz[77.75.76.32] said: 451 Local Error (in ...
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2answers
421 views

Postfix SMTP Relay Configuration Error

For the last day I was searching for solutions for this problem: My postfix(+dovecot) configuration is fully able to receive e-mails and to serve them via IMAP but it fails at accepting them via SMTP ...
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1answer
311 views

Postfix SMTP authenticated can send as anyone

The server correctly accepts/rejects the logins though dovecot's authentication mechanism, but after that I can pretend to be anyone when sending emails. smtpd_sender_login_maps = texthash:/etc/...
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1answer
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Postfix: How to make aliases work for virtual domains?

I'm trying to set up a local mailserver. I run Mac OS X Server 10.6 Snow Leopard, and it uses Postfix as server. I set the server up using the GUI and I'm doing all virtual settings via the terminal. ...
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2answers
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Easiest way to configure local SMTP server to relay through gmail on Windows?

We have gmail for our corporate email provider. I want to be able to send mail through smtp.gmail.com from ASP.NET. I have managed to do this just fine - and it has the benefit of all sent items ...
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3answers
519 views

Will mailing lists “break” if SPF is too restrictive?

I have recently configured my own mail server (Linux-based postfix + dovecot scenario). This is just for personal use - I have no bulk mail going out, no automatically generated mail outbound from the ...
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2answers
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Postfix - accept all email to any user at any domain

I need to configure an SMTP server to accept any email to any address that might happen to reach it on port 25 and deliver it to a local mailbox (i.e. a spam sinkhole) The default supported MTA on my ...
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How do I track whether a email was successful among thousands (IIS 6, .NET 3.5)

I want to be able to tell if an email sent to a user is successful or not. I've tried looking at the SMTP logs and there appears to be no way to link server requests with server responses. So if I ...
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6answers
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How to send Bulk email with SMTP server

How do email marketers get success while sending mails? Though their emails volume is very high, they can deliver mails with out any problem like spam or bounce. If we try to send bulk mails with our ...
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6answers
12k views

How can I set up sendmail to forward all mail to an external MTA?

We have multiple applications that currently talk SMTP to an external MTA. The emails have arbitrary destination domains (they're emails to be sent to our users), but all from the same internal domain ...
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2answers
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monit send email does not work

I am trying to use monit, and set up email server using gmail. The configuration file is like this: set mailserver smtp.gmail.com port 587 username "someuser@gmail.com" password "password" using ...
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5answers
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SMTP Reverse DNS Mismatch

My dedicated server ns382087.ovh.net resolves to 46.105.98.72 and hosts multiple domain with several dedicated IP addresses. Each new IP address is added to /etc/network/interfaces Among them, the ...
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2answers
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Sendmail on Ubuntu trying to use Google Apps servers as a relay, by default?

I have a recently installed Ubuntu (natty) server, with a domain pointed to it. The mail for this domain is handled by Google Apps (via MX dns records pointing to Google's mail servers). Now, I've ...
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What is causing email sent from my Google Apps account to bounce?

I have started to get Delivery Status Notification (Failure) messages in response to emails sent from my Google Apps domain account (at offby1.net): Delivery to the following recipient failed ...
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How to start SMTP [SMTP Virtual Server #1] through powershell or command prompt

Because of some error on my server my SMTP [SMTP Virtual Server #1] stop. I wanted to create job which will run periodic timely and check the SMTP server status, If its stop then it will start it ...
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1answer
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Log with iptalbes which user is delivering email to port 25

Because we got blacklisted on CBL I set up the following firewall rules with iptables: #!/bin/bash iptables -A OUTPUT -d 127.0.0.1 -p tcp -m tcp --dport 25 -j ACCEPT iptables -A OUTPUT -p tcp -m tcp -...
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2answers
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Postfix, saslauthd, mysql, smtp authentication problems

Trying to get authentication on my mail server (ubuntu 10.04) running but am having trouble. I have a server with postfix for smtp setup, imap server with courier setup. My postfix authentication is ...
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1answer
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How to set exim4 to send email anywhere but only from authorised users?

Struggling to get my head around the various relaying controls in the exim4 config. I can send email from my server, I can send email from home and work (because I explicitly added suitable netblocks ...
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1answer
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Dovecot - Unable to receive mail - Fatal: Plugin 'sieve' not found

Struggling to Dovecot/Postfix set up on Ubuntu 11.10, Dovecot version: 2.0.13, Postfix version: 2.8.5 I can send outbound mail using the mailx command, but I can neither receive mail or send mail ...
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smtp remote host responds “550 Sender verify failed”

A server I'm taking care of uses qmail for MTA. I can send and receive to almost every domain except one or two that give the following error, or something very similar: 550-Verification failed for &...
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3answers
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Sendmail : ignore local delivery

I've a Ubuntu webserver with Sendmail as my MTA Currently when i email outside my webserver's domain e.g. example.com to something like gmail or any other email outside the example.com domain it ...
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2answers
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SMTP 552 4.3.1 Session size exceeds fixed maximum session size

I'm having a frustrating problem with one of our clients who is running an exchange SMTP server. I have an emailing component that is written in .net and I've specifically used Mono DLL's to ensure ...
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1answer
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How can I configure Exim to drop non-authenticated connections on alternate SMTP port?

I currently only allow connections on port 25 from a mail filtering service's IPs. I have Exim running on an alternate port for SMTP submission. This port needs to allow non-encrypted connections ...
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1answer
159 views

Is there a way to “replay” a packet capture of a smtp session for the purpose of debugging?

I'm troubleshooting a smtp issue involving character-set encoding and it's extremely difficult to involve the end user. I have a packet capture of an incoming smtp session that results in problematic ...
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2answers
761 views

Intermediate SMTP server (exim), how to handle backscatter?

I have a dedicated Ubuntu Lucid box at a hosting provider that is my backup MX (running exim4 4.71-3ubuntu1.4) for domains that I have configured on an Exchange 2007 server on my LAN. So my Exim ...
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1answer
247 views

Simple, forwarding-only MTA?

I have a domain and a server. I’d like to have some e-mail addresses on the domain and I’d like to forward them elsewhere. I’d love to avoid running a full-featured MTA on the server, since they’re ...
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1answer
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Exchange 2013 recipient filtering - reject after RCPT TO

According to this forum thread, exchange 2013 has a new behaviour for recipient filtering. Apparently, mails to unknown users are only rejected after the DATA-Phase, not after RCPT TO as this was the ...
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1answer
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postfix misconfigured: “mail for (domain) loops back to myself”

I've just installed postfix on my debian system, so I have a default configuration, apart from the following values in /etc/postfix/main.cf: myhostname = mydomain.com alias_maps = hash:/etc/aliases ...
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1answer
180 views

Hot/Lukewarm mail server setup

We have two mailservers ("dubone" and "dubdeuce"), one does all the work while the other sits idle. We want to have a setup where if dubone is busy or down, dubdeuce can accept/reject/filter emails ...
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2answers
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How to remove the SMTP address for a secondary domain from all Exchange mailboxes?

I have an Exchange server which used to manage multiple SMTP domains; now it only has to manage one. I have already removed the secondary domain from all address policies; I need to remove all SMTP ...
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3answers
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Postfix relay host connection fails: timed out while receiving initial server greeting

I have an Elastix server box that I want to send email notifications of voice mails from. I'd like to send them through our company email (hosted by shared web host provider Bluehost). I have followed ...
4
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1answer
600 views

Is null return path reliable indication of a bounce?

I have a mailbox that receives bounces as well as normal email (the latter includes messages from automated services). I want to filter out the bounces and forward them to another mailbox. Assume I ...
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1answer
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Load balancing SMTP in a way that doesn't hide the source IP address

I need to load balance SMTP to handle some applications that don't know how to use MX records. I set up a Netscaler using the TCP option on port 25 and now Exchange sees the source IP as that of the ...