Questions tagged [smtp]

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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What ports to open for mail server?

I have just finished setting up a Postfix mail server on a linux (ubuntu) platform. I have it sending and receiving email and it is not an open relay. It also supports secure smtp and imap. Now this ...
radman's user avatar
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82 votes
6 answers
117k views

Do SPF Records For Primary Domain apply to subdomains?

I have a quick question regarding SPF records: Do they need to be present for all subdomains? Lets say that I have a TXT record with SPF info for domain.com Let's also say that I have a seperate ...
Mike B's user avatar
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73 votes
7 answers
492k views

How to correct Postfix' 'Relay Access Denied'?

This morning, in order to correct a problem with a name mismatch in the security certificate, I followed the recommended steps from How to fix mail server SSL?, but now, when attempting to send an ...
Noah Goodrich's user avatar
59 votes
10 answers
64k views

How to setup a fake SMTP server to catch all mails?

I'm looking for an smtp service that essentially obeys the RFC, except rather than sending mail it simply logs to a file [date] sent mail to <address> Or whatever. I can bash this together ...
richo's user avatar
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54 votes
5 answers
13k views

Is greylisting still an efficient method for preventing spam?

I've used greylisting on my servers for many years, but I don't know how effective it is nowadays. Is it still good for fighting spam in 2012? Or is the typical spammer MTA capable of resending ...
neu242's user avatar
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35 votes
2 answers
13k views

Postfix TLS over SMTP - RCPT TO prompts renegotiation then 554 5.5.1 Error: no valid recipients

I've setup ispconfig3 on my debian six server, and here is a little smtp over ssl: The server is postfix AUTH PLAIN (LOL!) 235 2.7.0 Authentication successful MAIL FROM: [email protected] 250 2.1.0 Ok ...
lol's user avatar
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35 votes
2 answers
17k views

SMTP allows for multiple FROM addresses in the RFC. Was this ever useful, why does this exist?

SMTP allows for multiple FROM addresses on the body (not the envelope) according to the RFCs. Has this feature ever been used for a legitimate purpose? Is it safe to discard messages that have ...
makerofthings7's user avatar
34 votes
2 answers
7k views

Sending malicious email as a test

I have set up a working SMTP relay together with MailScanner. This SMTP relay is not — and will not be — able to relay email from the outside, only local email. Is it possible to send a ...
Orphans's user avatar
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34 votes
1 answer
36k views

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 ...
Edwin Krause's user avatar
33 votes
3 answers
54k views

Automatically start SMTP server in IIS?

I'm running an IIS SMTP server in Windows 2008 R2 and it can be started manually. However, if I need to restart the system, I must manually start the SMTP server. Is there a way for it to start ...
user79537's user avatar
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30 votes
7 answers
74k views

SMTP server on Windows 7

Is it possible to install the SMTP server that you can install in Windows Server 2008 in Windows 7? Or something similar? I'm developing an application that will make use of it and I want to be able ...
Pablo Fernandez's user avatar
30 votes
4 answers
72k views

Legitimate reasons SMTP “MAIL FROM:” will not match “From:” Header in DATA

Is there ever a legitimate reason for the SMTP “MAIL FROM:” field to not match the “From:” field in the DATA section of a message, besides mailing lists? From https://stackoverflow.com/questions/...
dkovacevic's user avatar
30 votes
3 answers
79k views

Forcing encryption for outgoing SMTP with Postfix

Does anyone know how to tell Postfix to encrypt outgoing mail? I have configured it to use encryption on reception, but I'm unable to do it with the outgoing mail. This is my main.cf file: ...
Simon's user avatar
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30 votes
3 answers
59k views

What replaces IIS SMTP server in Windows Server 2012

I have read the notes here http://technet.microsoft.com/en-us/library/hh831568.aspx regarding deprecated and removed features in Windows 2012 and it says that SMTP is deprecated. I assume this is ...
Andy's user avatar
  • 499
29 votes
12 answers
275k views

IIS/SMTP - emails are stuck in mailroot/Queue

I'm trying to send e-mails via SMTP within the IIS pickup directory. Unfortunately the e-mails are just going into the mailroot/queue folder and stay there. They never actually get sent. Does ...
Jack Marchetti's user avatar
28 votes
5 answers
134k views

Postfix - Host or domain not found

I've just installed Postfix on my Ubuntu, on a local network. On this network, I have an Exchange Server (using domain mail.example.com). I had a problem sending an email to a local address: adress@...
Vincent LITUR's user avatar
27 votes
5 answers
37k views

What host name should the SSL certificate for an SMTP server contain?

I have a server foo.example.com at 192.0.2.1 It runs exim to receive e-mail for several of my domains. My domains each have an MX record pointing to mx.example.com, which resolves to 192.0.2.1 If I ...
David North's user avatar
26 votes
4 answers
138k views

Fixing My MTA's Poor Reputation

I have a web site that needs to send email to customers to deliver files that they have purchased. Reliable email delivery is vital to this business. Unfortunately, most of the emails sent by my ...
Alex Reisner's user avatar
25 votes
4 answers
65k views

What are SMTP relays and smarthosts?

What exactly is an SMTP relay, and what exactly is an SMTP smarthost? Can someone give me a brief description of each, including how they relate to one another?
LanceBaynes's user avatar
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25 votes
5 answers
163k views

Postfix Temporary lookup failure

I am trying to set up postfix, but I get a "Temporary lookup failure" error main.cf: inet_protocols = ipv4 inet_interfaces = all queue_directory = /var/spool/postfix command_directory = /usr/sbin ...
dzervas's user avatar
  • 363
23 votes
3 answers
6k views

Is an IPv6-only MTA possible yet?

Has anyone had tried to run an IPv6-only SMTP engine? Pretty much everybody with any sense has IPv6 configured for major front-end servers. I was curious if anyone had tried to run an IPv6-only MTA ...
joe's user avatar
  • 233
23 votes
2 answers
34k views

Are two periods allowed in the local-part of an email address?

A third-party email gateway relay is refusing to process a message for an email address we're sending to. The address is in the format of [email protected] (note the two periods)...
Mike B's user avatar
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22 votes
4 answers
27k views

Is it possible to send and receive an email from an IP address instead from a domain?

Usually an email has a domain name on the right side of the @, so you can identify an organization or a company. This domain is in fact nothing other than a "name" or an "alias" for an IP address, ...
user avatar
22 votes
2 answers
75k views

How to fix "unable to qualify my own domain name (myhost) -- using short name"?

and yes, I have 127.0.0.1 localhost myhost.mydomain.eu myhost.domain2.eu localhost.localdomain 127.0.1.1 myhost in hosts file. What is wrong? Sendmail started to put this error into log. May ...
user avatar
21 votes
2 answers
28k views

Correct use of SMTP "Sender" header?

Our web application sends email messages to people when someone posts new content. Both sender and recipient have opted into receiving email messages from our application. When preparing such a ...
Eric Rath's user avatar
  • 493
19 votes
4 answers
59k 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 ...
AlexMax's user avatar
  • 543
19 votes
1 answer
22k views

What is preferable, "no-reply@" or "noreply@"? [closed]

Having a service that sends out notifications to users, I'm currently thinking about changing the sender email address from "info@" to something more meaningful. Since a reply never makes sense, I'm ...
Uwe Keim's user avatar
  • 2,440
18 votes
6 answers
17k views

How to Setup Ubuntu Mail Server with Google Apps?

I have a domain, let's call it foobar.com. All of the MX records for foobar.com point to Google's mail servers because I am using Google Apps for your domain to manage it. It's great because everyone ...
Apreche's user avatar
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18 votes
2 answers
33k 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 ...
user avatar
17 votes
6 answers
118k 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?
Jason's user avatar
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17 votes
5 answers
197k views

Reverse DNS - how to correctly configure for SMTP delivery

I started a new service and we need to send emails to our customers (new account confirms, etc). My server is known as prod01.bidrodeo.com and resolves to 97.107.134.38 . For reverse DNS, 97.107....
Krystian Cybulski's user avatar
17 votes
2 answers
5k views

Is it still "wrong" to require STARTTLS on incoming SMTP messages

According to the STARTTLS Spec Section 5: A publicly-referenced SMTP server MUST NOT require use of the STARTTLS extension in order to deliver mail locally. This rule prevents the STARTTLS extension ...
jackweirdy's user avatar
16 votes
2 answers
2k views

What's the point of repeating an email address in "The Envelope" and the "The Header"?

I learned that both the FROM address and the TO address is repeated in a hidden element called the "envelope", and then repeated again in the "body". Question Why isn't the envelope data copied into ...
TLDR's user avatar
  • 311
16 votes
9 answers
85k views

Send an email with an attached file using telnet or netcat

I often use telnet or netcat to connect smtp servers to send an email as a test. Does anyone know how you would send an email using telnet or netcat but attach a file as well? There are probably ...
Kyle Brandt's user avatar
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15 votes
5 answers
36k views

When exim4 sends HELO/EHLO, how do I configure which host name it sends?

Mails from my system are being rejected when the receiving server does HELO checking. I believe my system is sending the wrong domain name. I'm running exim4. Googling for anything about exim4 and ...
user avatar
15 votes
2 answers
6k views

Gratuitous CRLF in Subject: line - why is it there, and is it legal?

I'm running into a problem with a NAGIOS system sending emails to a popular email-to-SMS service. The email-to-SMS service takes emails with text in the Subject: line, and sends them on to the mobile ...
MadHatter's user avatar
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15 votes
3 answers
13k views

What is the best method for sending email on behalf of my clients' domains?

I wanted to know the best way to make my mailserver send emails on behalf of my clients' domains, without being greylisted and also avoiding bounce problems. I've been reading some other questions ...
dgaspar's user avatar
  • 251
14 votes
1 answer
3k views

Security risk of POP before SMTP

I received an email from one of our servers this morning (CentOS, with WHM running LAMP) stating: The server has POP3 before SMTP enabled. For security reasons, cPanel highly recommends that ...
GeoffAtkins's user avatar
14 votes
2 answers
18k views

What does dis=NONE mean in an email's Authentication-Results header?

The following is from an email I received recently: Authentication-Results: mx.google.com; spf=neutral; dkim=pass [email protected]; dmarc=pass (p=REJECT dis=NONE) header.from=...
Alex Henrie's user avatar
14 votes
3 answers
5k views

Schedule/queue large e-mails in Exchange 2010, defer until latency drops

My challenge We have Exchange servers at various sites, but also aboard ships. The ships are connected to our network through satellite links when at sea, but switch to WiFi bridges when in port. ...
abstrask's user avatar
  • 1,698
14 votes
4 answers
4k views

Has anyone ever used SMTP site links?

A simple real-life question, inspired by a comment here: Active Directory has supported inter-site replication using SMTP instead of direct RPC since its first introduction in Windows 2000. But did ...
Massimo's user avatar
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13 votes
2 answers
4k views

Detect spammers on my server

I recently got one Undelivered Mail Returned to Sender while sending my newsletter to one of my 1500 customers. My website uses a double-opt-in procedure to make sure, the user explicitly want to ...
koseduhemak's user avatar
13 votes
3 answers
12k views

Why does DMARC operate on the From-address, and not the envelope sender (Return-Path)?

Several emails sent from my webserver to a Gmail address, where the From: address is [email protected], have been marked as spam by Gmail. The From: field is populated from form data, and ...
EelkeSpaak's user avatar
13 votes
1 answer
13k views

How can I configure Postfix to ignore relayhost for some domains?

Is there a way in Postfix to ignore the relayhost? I have something like relayhost = [smtp.domain.net]:587 Now for a certain domain I don't want to send it out to that relay but want it to just ...
Mike's user avatar
  • 22.5k
12 votes
2 answers
36k views

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 (...
Paralife's user avatar
  • 329
12 votes
3 answers
74k views

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 ...
Alistair Prestidge's user avatar
12 votes
3 answers
21k 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 ...
sohaibafifi's user avatar
12 votes
3 answers
44k views

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 &...
jfoucher's user avatar
  • 300
12 votes
3 answers
26k 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. ...
mine's user avatar
  • 197
11 votes
3 answers
9k 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 ...
thomasrutter's user avatar
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