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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In postfix, how to enforce tls + auth over 587 while leaving tls optional for 25

I would like to host mail services for some domains. I have succesfully setup postfix to consult sql for those virtual domains. What I would like to do is: For connections on 25: Deny relaying ...
7
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3answers
5k views

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
votes
5answers
39k views

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 ...
7
votes
2answers
2k views

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
13k 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 ...
7
votes
5answers
4k views

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 ...
7
votes
1answer
6k views

NOQUEUE: reject: RCPT from on freebsd and postfix

I am building a server using this config -> http://www.purplehat.org/?page_id=4 and when trying to test basic email capabilities I get -> NOQUEUE: reject: RCPT from when try to send a test email. ...
7
votes
3answers
10k 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
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3answers
7k views

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
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
6k 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
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5answers
20k views

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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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
2answers
4k views

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: ...
6
votes
3answers
14k 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 ...
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 ...
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
votes
1answer
53 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 ...
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votes
5answers
5k views

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 ...
5
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5answers
8k views

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 ...
5
votes
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
votes
3answers
426 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
votes
2answers
246 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 ...
5
votes
4answers
3k 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
votes
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
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2answers
674 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 ...
5
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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 ...
5
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2answers
255 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
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
votes
1answer
296 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
votes
1answer
533 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, ...
5
votes
2answers
6k 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 ...
5
votes
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 ...
5
votes
2answers
7k 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
4k 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
973 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
14k 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 ...
5
votes
1answer
3k views

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 ...
5
votes
3answers
15k views

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 ...
5
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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 ...
5
votes
1answer
113 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', ...
5
votes
1answer
866 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 ...
5
votes
3answers
21k views

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 ...
5
votes
1answer
2k views

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 ...
4
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6answers
605 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 ...