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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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Does SMTP accept "friendly" address in FROM line (in particular Exchange)

I have an application server sending mails with SMTP, and this application generates a FROM line that contains a "friendly address" that seems to be refused by Exchange, of the form: MAIL FROM: "Francois Barriere" The…
francois
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SMTP Server will not send to connected VPN domain

I have a Windows 2012 web server that is connected to a company's VPN (vpn.company.com) to access network resources and needs to send emails to users of that company as well. When the web server is not connected to the VPN, emails can be sent to…
tiki_master
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Setting up SPF records on dedicated server

I have a question in regards to SPF records in a dedicated hosting environment. I wish to set up an SPF record for my dedicated server, but I am not sure whether my understanding is correct. First question: Do I need to set up the SPF record for…
Shane
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Postfix Relay Based on Recepient

What is the best practice when one has to implement this sort of ruleset in postfix? Email sent to a@example.com, b@example.com, etc ought to be relayed to smtp.a.example.com. Email sent to [everyone else]@example.com ought to be relayed to…
Chris Smith
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Why is my email being rejected?

I am having problems sending an email from one email address to another on my domain. I am using a shared server. I use weather software which automatically constructs and sends the email message. I have omitted the host, domain and IP info and…
Ross Hodgman
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Overriding selected recipients using postfix

Is it possible to have some kind of regex match and replace, like it is possible for outgoing mails for incoming, too? I am already able to replace the from field for outgoings, by using the smtp_generic_maps option. Now I'd like to apply the same…
Coxer
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Diagnose SASL LOGIN authentication failure with postfix and sasldb

I am trying to configure a Postfix SMTP server on my personal machine (ubuntu server) using sasldb2. So far what I have set up works well with the test command: testsaslauthd (however it may be worth noticing that I have to do a chmod+x on…
user3484865
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Do I need SMTP when using Postfix/Dovecot?

I have setup Postfix and Dovecot. Microsoft outlook tells me it cannot find the SMTP server. I thought dovecot would handle all the deliveries? Do I need to allow postfix to listen to external connections on port 25 too? Thanks
ego
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migrating to new server, would like to keep sending email from existing server

Hello I'm in the process of moving my site to a new host (ie new IP). I run a social site that sends a large volume of (valid) email, and I have built up a good sending reputation with my current IP over the last 2 years. My migration plan generally…
Sherif Buzz
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Postfix on two servers. Can I route all mail though just one of them?

I have at least two web servers which utilise Postfix to send mail from web applications. One is what I call the 'master' which will remain static and the other is what I call the 'slave', which is cloned often for load distribution. Each clone is…
MrNorm
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Sending mail from PHP gives Unrouteable address

I have a Debian server running PHP and Exim4 (among other things of course). The PHP application is sending 1000s of emails every day all of which work fine, however I now have a new customer and my PHP/Exim4 has trouble sending to this account. PS…
muz the axe
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Using IIS smtp for incoming and outgoing and use hMailserver for mail accounts

I have installed hMailServer in one machine and IIS STMP in another machine. Even though hMailSever itself is a SMTP server. I can't avoid this because the IIS SMTP server has some hooks which which encrypts and decrypts the incoming and outgoing…
user214823
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If I use postfix for mail relay, so is myhostname / mydestination important?

I use postfix to relay mail to 3rd party SMTP and never sent out email directly, and of course I never receive email. So If I set myhostname / mydestination to sth like fake.mydomain.com, which mydomain.com is valid domain, but fake.mydomain.com…
Ryan
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Exim routing based on individual email addresses

I am trying to migrate individual users, one at a time, from an Exim based mail system to an Exchange 2010 system. I'm hoping to do this by leaving the Exim based system as the MX for the time being, and as a user mailbox is created on the Exchange…
rvf
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What is the correct way to get an NDR to be sent when a bounce back occurs?

I have a user who developed a WebApp that sends SMTP messages. Users are able to reply to the message using a MUA (outlook, whatever) but there is no NDR if the user doesn't exist. I suspect that the envelope is empty or missing and only the body…
makerofthings7
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