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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

3133 questions
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SMTP unroutable address

I have set up gmail google app accounts for our own domain, domain.com, so that email is handled by gmail. I.e. MX records point to google servers, A records to our own server IP. This works fine. Now I tried sending emails from our machine (via…
fiscal_policy
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Secure POP3/SMTP proxy?

An ISP doesn't offer secure/encrypted POP3/SMTP connections to its email servers. (I could forward the mail to another mail service that does, but I'd like to try a proxy) Is there some simple software that could be run on a linux box to allow…
chibi
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My mailserver is getting stuck in http://cbl.abuseat.org/

I have a small system that sends about 15 email/day to my personal email account. I have set up the web form so that the users email is set as sender when I send the email to my inbox so it's easy for me to answer with just a reply. The problem is…
Andreas
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SMTP Error "check for new mail first"

I need to send e mail from a asp.net web site. The mail server is not in same network with the web server (it's in different location). Sometime it sends the mail without any error, but sometimes it does not work and gives an error saying, Mailbox…
Nalaka526
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Messages stuck in SMTP queue - Exchange 2003

I need your help people ;-) I have a problem with messages coming into our Exchange Server and ones going out through it. Basically, the messages are stuck in the SMTP queue. A message will come into the server, I can see it listed under "Exchange…
Diav
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Exchange Server is rejecting message after "MAIL FROM" with "500 5.3.3" with tarpit despite being a Trusted Receiver

I'm getting the message: "500 5.3.3 Unrecognized command" from Exchange server and seeing in the Exchange Server logs that it's tarpitting my smtp sender despite the fact that: I added a Receive Connector for my ip that allows connection, uses…
Don Rhummy
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DNSBL - Email Servers Spam

I'm currently doing research on a better way for emailing customers our news letter and not using an ESP such as vertical response since most users there use purchase list and ruin the shared IPs for everyone. My question is, do you really need to…
kernelPanic
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Append to outgoing e-mail on ExIM the proper way

We are a small charity organization running ExIM for our emails. Is there a proper way to configure ExIM to append links to our facebook and twitter profiles to every outgoing mail? I found this ExIM wiki page Modifying message bodies, which states…
Framester
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Can't connect to smtp (Exim)

If I type: telnet localhost 25 into SSH, it says: Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. Connection closed by foreign host. However, when I type: exiwhat into SSH, it says: 28543 daemon: -q1h, listening for SMTP…
John
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How to get Windows Mail (Vista) to send mail?

It's throwing a "Socket Error: 10060, Error Number: 0x800CCC0E" error on send attempts. So far my googling and binging reveals that a lot of other people seem to have the problem, but none of the listed solutions help. Note that this was a clean…
Brian Knoblauch
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Exchange 2007 relay from sendmail, message "Undelivered". Possible reasons?

Note: This is my re-post from Stackoverflow. I've been messing with a test environment for security purposes where a DMZ RHEL5 sendmail server is used as a relay for an Exchange 2007 server. Exchange is working in the environment, I have Vista and…
dubmojo
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Sending email to a remote user which has the same domain name

My smtp servers domain(origin) is xxx.com. When I try to email user51@xxx.com from smtp server, it does not deliver that mail since this user51 is not hosted on this smtp server. user51 has an google apps account with domain xxx.com So I want smtp…
Oguz Bilgic
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How can I easily set up an email server for development purposes?

I'm developing a webmail UI, but I can't use Mailgun or my Gmail account, as I need public and shared namespaces. I tried to install Dovecot, but it required tons of configuration. Is there a server that is easy to configure and run? Or maybe an…
Pepijn
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Qmail SMTP Whitelist & SMTP Authentication?

How can I get qmail to work with both an smtp whitelist and smtp authentication? If my IP is whitelisted, SMTP authentication does not seem to work (error: "the server does not support SMTP password authentication). This is particularly annoying…
ck86
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What should be the spf record for my domain?

I have my own registered domain. I have a dedicated IP for my domain. I use a shared hosting service for my website. I want to send mail with php's function mail();. I have created one email account with my domain name. The problem is that all the…
ecantu
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