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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.

Some characteristics of SMTP (Simple Mail Transfer Protocol):

  • The default port is TCP port 25 and new submissions (MSA) is port 587.
  • Although depreciated, some services still use port 465 (SMTPS) to support legacy applications.
  • It is used to transmit outbound mail, and mail servers (which listens on port 25) receives mail on port 25.
  • It should not be confused with POP3 / IMAP which is an actual store for the e-mail. SMTP messages are received by the receiving server and then an MTA moves it to the POP3 / IMAP mailbox where it is normally retrieved using a POP3 / IMAP client.

See Also:

RFC5321

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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 is a pretty beginner question but should I be…
radman
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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 email domain for subdomain.domain.com Will the SPF…
Mike B
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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 email from a client (in this case the client is…
Noah Goodrich
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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
Or whatever. I can bash this together with the bare minimum of functionality I need in python in…
richo
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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 greylisted emails now?
neu242
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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 multiple FROM addresses?
makerofthings7
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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: lol@lol.com 250 2.1.0 Ok RCPT TO: lol@lol.com RENEGOTIATING depth=0…
lol
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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 malicious email with the terminal? I have googled around but…
Orphans
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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 automatically on boot? Thanks
user79537
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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 also see that there are possible settings for smtp…
Edwin Krause
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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 to test it and try it locally.
Pablo Fernandez
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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…
dkovacevic
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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 referring to the IIS SMTP server. The advice is to…
Andy
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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: smtpd_recipient_restrictions = permit_sasl_authenticated,…
Simon
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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 anyone know why this would happen and a potential fix…
Jack Marchetti
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