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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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Virtual SMTP Server not relaying mail

In our LAN, we have a development box with IIS 7 that has an SMTP Virtual Server installed. All development applications send outgoing mail to this virtual SMTP server, and it in turn relays the mail to our internal Exchange 2007 server. Or, at…
Jacob
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iRedmail, smtp on port 465 isn't working and appears closed

I just installed iRedMail on Ubuntu 12.04 lts, fresh install following the tutorial on their website. Everything functions well, including webmail, however sending mail over smtp (port 465) doesn't work at all and I also cannot telnet to the server…
damnyouiredmail
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Control which users can authenticate with Windows SMTP Server

Is it possible to control which users in a domain can connect to the Microsoft IIS SMTP server? How is this managed? Specifically, is it possible to restrict this to a single user? The server is in a domain, but will only be used for a single…
toryan
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What SMTP header allows me to control the MFROM address used in MTAs?

I need to send out an email with a custom Reply-To header and has a particular value for MFROM. (the message envelope) I have the choice to send though IIS SMTP, or Microsoft Exchange Server, and both of them relay through a managed service. IIS …
makerofthings7
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Set Windows Server 2008 R2 SMTP for Opportunistic TLS

I use a Windows 2008 R2 server for sending (relaying) outbound emails to clients. Many of these clients are now requiring TLS connections to send them email. To date I have set up a an SMTP "Remote Domain" and forced TLS to that domain. Keeping…
Brettski
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Reverse DNS lookup not resolving correctly

I've been searching and searching for the answer and I can't find it. My problem is that all of my emails sent from my server are either going to spam folders or not being delivered. I am trying to apply for jobs, but I can't do that if all of my…
DataCorrupt
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Forwarding all mail to a single dev box on IIS via virtual SMTP

I am trying to set up a development environment for our web server. I would like all emails that are relayed by the server go to a specific mailbox, regardless of who they were sent to. For example, some application on the server sends an email to…
Greg R
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Postfix - unable to access externally

So I can't seem to access smtp from externally. When using a desktop email client (eM client and thunderbird both fail) I can't get it to hit the server at all. (eM client is trying to hit: smtp://xxx@mail.xxxxxx.com:25 if that helps) I looked…
Aram Papazian
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iptables blocking access to SMTP on port 25

I have iptables running on my server that blocks access on all ports except the ones I allow. One of those ports needs to be SMTP on port 25, and I have the following rule in place for that: -A INPUT -p tcp --dport 25 -j ACCEPT The output from…
Chris
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Mail stuck in queue folder using IIS 6.0 SMTP server

I have finished setting up my server but when I sent email it got stuck in queue folder. This was a test email which I put in pickup folder. So I checked my log file. I have pasted the log files here. I have been looking for solution but none…
Sithelo Ngwenya
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Set up a Postfix server on Ubuntu for use with Apple Mail (or any mail client)

I set up a Postfix server on my Ubuntu VPS and it works for sending email from the mail utility in the command line. I set up SPF records, DKIM, pretty much everything I could read about. However, I'd like to be able to send and receive email…
tekknolagi
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Are generic reverse DNS entries acceptable for an outgoing SMTP server?

Our PTR records are managed by our ISP, as our ranges are too small for them to consider delegating to us. So, every time I want to update an entry, I have to email their support team. In an effort to keep things simple, I'm considering asking them…
BJT
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Sending bounce mail messages customized for employees no longer with the company

Currently we use a hosting company for our Exchange services. We are considering a switch to Google apps, but that is in a pilot program at the present time. Our Exchange provider and Google Apps both have the ability to send e-mail that has been…
Richard West
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How much mail will be lost if I only support SMTPS?

If I configure my locally hosted SMTP server to only accept SMTPS connections (secure SMTP port 465/587), how much mail will I lose because sender(s) don't support sending on SMTPS? Are the major mail providers fully complaint of SMTPS on 587?
slacy
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Exchange 2013 Internal Relay via Smart Host

Thank you for your help in advance! I am currently setting up an Exchange 2013 server, to replace our old POP3/SMTP system, however we would like to roll this out gradually when convenient for our staff. Our plan is therefore: Setup Exchange 2013…
Matt Clements
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