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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fake “from” field in an email

How can I manipulate the "from" field in an email and make the "to" user see something different then the actual. Example: really from From: TStamper@yahoo.com but they see From: Tremayne "...
7
votes
2answers
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Why is email being delivered normally despite an SPF “hardfail”?

I'm trying to figure out why forged email is being delivered to major email providers (gmail.com, outlook.com) even though email is marked with an SPF hardfail. The email is also delivered to ...
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votes
7answers
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Very simple SMTP server for Ubuntu wanted

I'm looking for a very simple, lightweight SMTP server to run on an Ubuntu 9.04 VPS. The only functionality I need is to support the PHP mail command; <?php mail('caffeinated@example.com', 'My ...
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votes
5answers
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Easiest way to send a test email from a server, to test settings?

Using Windows (2008) is there an easy command line tool that I can use to send a test email from a server to test the SMTP, user authentication, ports, etc... without writing my own?
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6answers
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Recommended personal mail server setup [closed]

I've been using GNU/Linux for servers, mostly Debian. I am thinking of keeping my personal email on a centralized server. I have some GMail accounts, and a few from different domains from several web ...
7
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2answers
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Can't get SASL auxprop/sasldb working with postfix/Ubuntu 12.04

I have an Ubuntu 8.04LTS system running Postfix 2.5.1. On that system SMTP AUTH runs fine. The contents of /etc/postfix/sasl/smtpd.conf are: pwcheck_method: auxprop auxprop_plugin: sasldb mech_list: ...
7
votes
3answers
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In the mail header, what does the “received from” ip refer to?

I noticed that some mail header contact a field called received : from and it contains an ip address. Does this address refer to the sender machine even if he is using a web interface or to the ...
7
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5answers
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Temporary failure in name resolution : Host name lookup failure

I've got a script in PHP that's been running fine for months. It recently stopped working. This script connects to gmail to send out an email to my customers. Recently, I started getting this error ...
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2answers
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Can I have an MX record for a 3rd level domain?

I have mail working for continuumconcepts.com right now. My mx records point to my assigned google postini servers. Works great. I have another server out in the wild that is completely disconnected ...
7
votes
4answers
14k views

Disable SMTP AUTH on Port 25

Due to PCI-DSS, we are required to disable plaintext authentication. We've achieved this by encapsulating communications between our mail server and clients with TLS on port 465. The problem lies in ...
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5answers
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Is the IIS SMTP Server good enough for a production server?

I was planning to use the SMTP server that comes with IIS7 (for a website) but then I came across this link and started to get worried (read the accepted solution), on the other hand I have a limited ...
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3answers
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IIS6 Virtual SMTP server isn't coming back up automatically after a system restart

I've got a virtual server running Win2008 RC2. I've set up IIS6 with a virtual SMTP server on it to be the mail provider for the websites I'm hosting there. It all works great, but if for some reason ...
7
votes
3answers
12k views

Roundcube & Postfix SMTP: SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca:s3_pkt.c

I have a Postfix / Dovecot / Roundcube setup that I use personally, as well as provide to other users. I am attempting to transfer this entire setup to a new box, but having some issues. Mail ...
7
votes
1answer
102 views

Trying to setup mail server, can't get ports (25, 587) to work

I've searched everywhere and I'm really struggling with this one. I think I've tried just about everything. Background info VPS with CentOS 6.7 Postfix 2.6.6 dovecot, amavis, mysql, fail2ban I've ...
7
votes
1answer
1k views

Cisco FWSM -> ASA upgrade broke our mail server

We send mail with unicode asian characters to our mail server on the other side of our WAN... immediately after upgrading from a FWSM running 2.3(2) to an ASA5550 running 8.2(5), we saw failures on ...
7
votes
1answer
7k views

postfix sasl “cannot connect to saslauthd server: No such file or directory”

I try to setup postfix with smtp authentication. I want to use /etc/shadow as my realm Unfortunately I get a "generic error" when i try to authenticate # nc localhost 25 220 mail.foo ESMTP Postfix ...
6
votes
1answer
3k views

How can you test a backup / secondary MX server?

I'm wanting to set up a secondary MX server using Postfix but I am wondering what is the best way to test this prior to putting into production (by adding its MX entry)? One possible way is to test ...
6
votes
2answers
2k views

Display a TLS icon for messages that are TLS secured (Outlook)

One of my colleagues at a large financial institution has customised Lotus Notes to show a TLS icon for messages that are TLS secured. I'm interested in imitating this feature in Outlook, and believe ...
6
votes
3answers
15k views

Google SMTP Error: 454 4.7.0 Too many login attempts, please try again later

I discovered that while it was possible to use Gmail/Google Apps as an SMTP server for scripted use, if too many emails were sent I started getting error messages: SMTP Error: 454 4.7.0 Too many ...
6
votes
2answers
1k views

Expose IIS SMTP Pickup folder as a file share - bad idea?

Environment: IIS Web Farm 5 servers Windows Server 2008 R2 IIS 7.5 ASP.NET 3.5 and 4.0 web application Our web app, like many, needs to send mail. Send only, no receiving. In the past, we've ...
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votes
2answers
7k views

How can I configure my postfix server so reject_sender_login_mismatch doesn't block aliases of the main account?

I've recently setup postfix, dovecot, amavis and a suite of other tools using iRedMail, and I'm having difficultly authenticating to my outgoing mail server. The issue is this: xyz@mydomain.com is ...
6
votes
1answer
6k views

Windows Server 2008 SMTP Server is not writing to log file

I use Windows Server 2008 as my development operating system. I have been able to test that the SMTP Server on the machine can successfully send emails (I receive them in my inbox) but the log file ...
6
votes
1answer
27k views

How to configure sendmail to send email via GMail (smtp.gmail.com), using port 465 or 587?

I have configures sendmail to send email via my GMail (Google Mail) account, i.e. via smtp.gmail.com, by editing /etc/mail/sendmail.mc and regenerating sendmail.cf: -dnl define(`SMART_HOST',`smtp....
6
votes
2answers
3k views

Setting up two Exchange servers to receive mail on their old domains while sending and receiving using the same new domain

The scene: A merger of two companies. One running Exchange 2010, the other Exchange 2003, both having Active Directory Schemas at Server 2003, SP 2. Short term goal: Establish a trust between both ...
6
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3answers
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Exchange Connector Won't Send to External Domains

I'm a developer trying to get my .Net application to send emails out through our Exchange server. I'm not an Exchange expert so I'll qualify that up front!! We've set up a receive Connector in ...
6
votes
1answer
55 views

How Does Low Volume Affect (esp. live.com) Email Deliverability?

I've been sending emails for years with out any serious reputational shocks, but with low IP volumes (no bulk mail or automated transactional email), even with multiple Domain names. My Gmail ...
6
votes
1answer
1k views

Windows Server 2012: Cannot install SMTP-Server, system always requires restart

I'm not able to install the "SMTP-Server" feature on a Windows 2012 server. The installation process always fails with a "restart required" message. After the restart and (re)starting the SMTP-Server ...
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votes
5answers
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Many ISP's is block port 25, how do I choose an alternative port?

I am building an application that will be acting as a combined MUA/MTA on different networks. However, many of the networks are with ISP's that block port 25 for SMTP. Therefore I would also like to ...
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votes
8answers
5k views

How do I add outbound only mail service for local tools to a 'minimal' debian system?

I have several servers running applications on debian. Each has the packages it requires for the application, and no more. Currently, none have mail sending capability. However, I would like the ...
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5answers
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Outgoing only SMTP server

I want to setup an outgoing only SMTP server on Debian, so my Web-applications will be able to send e-mails via it. I don't want to use another hosts because of security and customizability of my own ...
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3answers
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mail loops back to myself | postfix

Hi I have an issue with bounced mail it does not happen all the time but at the same time is very frequent. Most of the time if I send an email to an address that does not exist then i get a bounce ...
5
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3answers
438 views

(How) do you run “functional” tests on your services automatically?

Consider a simple FreeBSD machine running an SMTP server - how can I automatically verify that it's doing the right thing (e.g. accept incoming SMTP connections for certain recipients, and drop the ...
5
votes
3answers
2k views

Exclamation marks being inserted into Emails at approx 1000 character mark

Have a .NET program that uses the System.Net.Main namespace to send an email via SMTP. Its on a customers site so from there it will go via a (series of?) SMTP relay servers before it reaches its ...
5
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1answer
835 views

Postfix reject_unknown_reverse_client_hostname: replace default unknown_client_reject_code (450) to 550. Why/When I should not?

In the daily battle against SPAM, there have been several times when I've been tempted to heavily enforce DNS requirements from clients connecting from the wild Internet. In detail, I would have ...
5
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2answers
249 views

What is the difference between 3-digit and dotted SMTP error codes?

When looking up SMTP error codes, I sometimes see "550", or "5.5.0". And sometimes the number in the dotted code is different. I found the numeric codes defined in RFC 821 and the dotted codes in RFC ...
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4answers
4k views

Reject incoming emails that use your own domain as sender

It would be nice to reject incoming emails which use one of my virtual domains as sender address while not being a legitimate user of mine. I know that I can reject incoming emails which use an ...
5
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3answers
99 views

What to do if one doesn't want to receive email bounces?

Background—the standards RFC 5321 §4.5.5 states: All other types of messages (i.e., any message which is not required by a Standards-Track RFC to have a null reverse-path) SHOULD be sent with ...
5
votes
1answer
4k views

postfix multiple IP SMTP banner

I've installed postfix 2.11.3 and we have multiple IP addresses on our server which we want to host two domains, isolated and running on their own IPs. domain1 unix - - n - - ...
5
votes
2answers
685 views

Load Balance Mail Gateways

I am currently trying to find a way to Load Balance our 4 Mail Gateways ( Running Mail Cleaner). I was able to bring up HAProxy and use tcp mode to load balance without issue. The only real problem ...
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2answers
2k views

Custom headers in Email lost?

I have some questions about custom mail headers Does anybody know of any mailserver which deletes proprietary/custom headers when being transmitted to its destination? Is there a header you can set ...
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2answers
256 views

How to allow login to a SMTP server better than with password?

I'm planning on creating a mail server, but I don't want to use passwords at all. They seem a wrong security choice to me. I'd love to use a certificate to login. This seems easy to do in HTTP, but I ...
5
votes
2answers
2k views

Is setting up my own SMTP server to send email a waste of time with regards to deliverability?

I have a dedicated host serving a few domains I manage. I host my own email and IMAP server. The server is at buildoneforme.com with IP address 144.76.81.247. I think reverse DNS is working: $ host ...
5
votes
2answers
1k views

Exchange Server vs. IMAP

I've been using a hosted exchange server environment (dslExtreme) for years. Originally, I used it w/ Outlook, but now that I have a Mac, I use Entourage. I also use my iPhone to connect to my ES ...
5
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1answer
331 views

postfix dovecot disable lmtp

I have 3 servers. 1 MX server with postfix and 2 dovecot servers. MX server receive emails and then serve them through LMTP to specific dovecot server. All mailboxes from same domain are on same ...
5
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1answer
545 views

Postfix SMTP sends to localhost, ignores MX records set to Google Apps

I have the MX records for zaltin.com set to the Google Apps domains (aspmx.l.google.com etc.). If an email is sent to kerrick@zaltin.com from most places, it goes to my Google Apps account. However, ...
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1answer
2k views

Exim TLS and Secure SMTP

I'm in the process of converting an existing mail server to support encrypted SMTP for our clients, but I've run into this brick wall with very little useful log data to help me forward. Everything ...
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2answers
8k views

How to setup a Postfix SMTP-only for multiple domains

This is my first question on Stacks. I always read a lot of solutions to problems here almost every other day. So thank you to all contributors. I am a noob here so please spare some space if I am ...
5
votes
1answer
5k views

SMTP authentication failure + PAM-MySQL cannot authenticate

I am building a mail server using Postfix, and set up the authentication to check against a database set-up using Postfixadmin. I can authenticate via Courier IMAP okay, as it can authenticate ...
5
votes
5answers
980 views

SMTP server, SPF records, domainkeys

Recently we have setup a new SMTP server to send newsletters and promotional mails to our registered users. There are 5000 users who will receive newsletters on weekly basis. We are getting bounced ...
5
votes
2answers
15k views

554 5.7.1 <mail_addr>: Relay access denied centos postfix

I have problem in send mail from postfix in centos I have following setup mail server postfix for sending mail but I am getting error. As in the link I tried following commands telnet localhost ...