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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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Setting the IP address that the SMTP service uses in Windows Server 2008

My ASP.NET application running in IIS7 on Windows Server 2008 needs to send email. I added the SMTP feature to Windows Server 2008. The problem is that my server has multiple IP addresses and I don't seem to have any control over what IP is used…
Ben Mills
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postfix and iRedMail- Relaying Denied

I am trying to setup iRedMail and am way over my head here. I have installed it, and can send emails internally, but not externally. When I send an email from outside, I get the following return email: The error that the other server returned was:…
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postfix with mailman

What should happen is that user@dur.bounceme.net should be delivered to that users inbox on localhost, user@localhost. Thunderbird works fine at reading user@localhost. I'm just using a small portion of postfix-dovecot with Ubuntu mailman. How can…
Thufir
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DSN Service Unavailable

I am having trouble with a newly installed server that we have just migrated to. I am running sendmail and cannot send mail to a specific domain. Mail everywhere else appears to work. Logs say: DSN: Service unavailable Weirdly, I get a Message…
Lock
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What is the failover logic when SendMail is smarthosting to a FQDN with multiple A records?

CentOS 5.x | SendMail This is somewhat related to my other question about round robin but as it's more general, I thought I'd separate it out. If SendMail is smarthosting to a FQDN with multiple A records and it can't reach the first host it…
Mike B
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Capture SMTP traffic over long time period

We have an SMTP relay (just an XP box with SMTP) on our network. It's hanging around because some legacy apps used to use it so send emails from code. It hardly gets any traffic, I can see from the SMTP log that it's only used every few days, if…
Ben
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Exchange 2003 missing default SMTP connector, but still routing through smarthost

I have an Exchange 2003 server currently using MXLogic as a smarthost, relaying all outbound mail through it. I confirmed this by sending mail outside the domain and checking the headers. I need to modify the smarthost I'm using, but I can't find…
ndespres
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Can a webmail client interact directly with the SMTP server? (without IMAP)

I'm trying to understand how all the components of a mail server fit together. I understand that the SMTP server is necessary to send emails. In terms of accessing email, I'll setup a webmail client but do not need access through a desktop…
sameold
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Disable local delivery ONLY for authenticated users in Qmail

We are moving some mailboxes and servers. I'm looking for a way to use remote delivery (with normal MX lookup) instead of local delivery ONLY for authenticated users, in Qmail. connection to port 25 without auth => allow delivery to local…
Antares
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convert messages in transit from UUEncode to MIME

I have a third-party app that generates emails in UUEncode format with PDF attachments. The PDF attachments are unreadable because iPhones don't understand UUEencode apparently. I don't see any settings anywhere in Exchange 2010 to make the Exchange…
longneck
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Postfix Is it possible to rewrite From: field to email used in authorization procedure

It's known that users can provide any email in From: field. I need to prevent it by rewriting it to email used in authorization procedure. Is it possible to do in postfix? Or may be other MTA?
Alexey
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How does “sendmail” send mails to any domain name?

I noticed that one of our servers (running Ubuntu) can send mails to any domain (yahoo.com ,gmail.com) using simple "sendmail" command. But I cannot figure out how to configure similar setup in a new server. I cannot see any files such as…
Ashika Umanga Umagiliya
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IP Tunneling for SMTP server on Windows 2008?

I have a Windows 2008 server that is running an SMTP server. The server has a public IP Address. I have 2 other windows servers, not in the same network, that are used for hosting client applications. We have a need to make sure that the emails sent…
Robert Class
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Use Gmail as smtp over services like Sendgrid

From an web app, we need to send around 1000 emails per month to different people. Is it a good idea to use smtp.gmail.com instead of Sendgrid, MailChimp or similar? Does Gmail impose any upper limit to the number of emails one can send?
intellidiot
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smtp relay only works on gmail accounts

I have a client who has a server but does not host their own email. They have just purchased a MFC and want to scan-to-email. I have them set up to send mail to gmail, however if they try to send to an email address outside the gmail network it…
msindle
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