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.

learn more… | top users | synonyms

4
votes
3answers
4k views

Anyone have a Powershell script to look up the MX record for a domain?

I want to check to see if the email addresses in my contact management system are valid and the best way I can think to do this is to get the MX record for their domain, then open an SMTP connection ...
4
votes
2answers
97 views

Spam addressed to a sender but received by everyone else

Spam's been getting through Postini lately that's addressed to a recipient (bob@example.com) in the To: field and in the headers. While this isn't that strange -- we've had spam get through before -- ...
4
votes
4answers
6k views

SMTP relay through GMail overrides “from:” address with “[me]@gmail.com”

I've been trying to figure out if this is a new "feature" or if there is an issue with my configuration. I'm using Ubuntu 10.04 Desktop with Postfix as MTA. My smtp (as opposed to smtpd) ...
4
votes
5answers
35k views

How do I configure reverse DNS for a SMTP server [duplicate]

We use iis 6 to send out emails for our website but some email addresses bouce backs. It only appears to be 2 addresses. There is at least 100 different email addresses sent to at the same time as ...
4
votes
3answers
247 views

Foreign mail server returns “502 Command not implemented.”

I am using Postfix to communicate with foreign server and send a mail. Every time when I try send mail using Postfix, I get this error: (host mx2.seznam.cz[77.75.76.32] said: 451 Local Error (in ...
4
votes
2answers
340 views

Postfix SMTP Relay Configuration Error

For the last day I was searching for solutions for this problem: My postfix(+dovecot) configuration is fully able to receive e-mails and to serve them via IMAP but it fails at accepting them via SMTP ...
4
votes
1answer
270 views

Postfix SMTP authenticated can send as anyone

The server correctly accepts/rejects the logins though dovecot's authentication mechanism, but after that I can pretend to be anyone when sending emails. smtpd_sender_login_maps = ...
4
votes
1answer
14k views

Postfix: How to make aliases work for virtual domains?

I'm trying to set up a local mailserver. I run Mac OS X Server 10.6 Snow Leopard, and it uses Postfix as server. I set the server up using the GUI and I'm doing all virtual settings via the terminal. ...
4
votes
2answers
25k views

Easiest way to configure local SMTP server to relay through gmail on Windows?

We have gmail for our corporate email provider. I want to be able to send mail through smtp.gmail.com from ASP.NET. I have managed to do this just fine - and it has the benefit of all sent items ...
4
votes
1answer
436 views

Postfix reject_unknown_reverse_client_hostname: replace default unknown_client_reject_code (450) to 550. Why/When I should not?

In the daily battle against SPAM, there have been several times when I've been tempted to heavily enforce DNS requirements from clients connecting from the wild Internet. In detail, I would have ...
4
votes
2answers
2k views

Postfix - accept all email to any user at any domain

I need to configure an SMTP server to accept any email to any address that might happen to reach it on port 25 and deliver it to a local mailbox (i.e. a spam sinkhole) The default supported MTA on my ...
4
votes
2answers
10k views

How do I track whether a email was successful among thousands (IIS 6, .NET 3.5)

I want to be able to tell if an email sent to a user is successful or not. I've tried looking at the SMTP logs and there appears to be no way to link server requests with server responses. So if I ...
4
votes
6answers
9k views

How to send Bulk email with SMTP server

How do email marketers get success while sending mails? Though their emails volume is very high, they can deliver mails with out any problem like spam or bounce. If we try to send bulk mails with our ...
4
votes
1answer
2k views

postfix multiple IP SMTP banner

I've installed postfix 2.11.3 and we have multiple IP addresses on our server which we want to host two domains, isolated and running on their own IPs. domain1 unix - - n - - ...
4
votes
3answers
362 views

Will mailing lists “break” if SPF is too restrictive?

I have recently configured my own mail server (Linux-based postfix + dovecot scenario). This is just for personal use - I have no bulk mail going out, no automatically generated mail outbound from the ...
4
votes
5answers
19k views

SMTP Reverse DNS Mismatch

My dedicated server ns382087.ovh.net resolves to 46.105.98.72 and hosts multiple domain with several dedicated IP addresses. Each new IP address is added to /etc/network/interfaces Among them, the ...
4
votes
2answers
3k views

Sendmail on Ubuntu trying to use Google Apps servers as a relay, by default?

I have a recently installed Ubuntu (natty) server, with a domain pointed to it. The mail for this domain is handled by Google Apps (via MX dns records pointing to Google's mail servers). Now, I've ...
4
votes
6answers
3k views

What is causing email sent from my Google Apps account to bounce?

I have started to get Delivery Status Notification (Failure) messages in response to emails sent from my Google Apps domain account (at offby1.net): Delivery to the following recipient failed ...
4
votes
2answers
4k views

Postfix, saslauthd, mysql, smtp authentication problems

Trying to get authentication on my mail server (ubuntu 10.04) running but am having trouble. I have a server with postfix for smtp setup, imap server with courier setup. My postfix authentication is ...
4
votes
1answer
4k views

Dovecot - Unable to receive mail - Fatal: Plugin 'sieve' not found

Struggling to Dovecot/Postfix set up on Ubuntu 11.10, Dovecot version: 2.0.13, Postfix version: 2.8.5 I can send outbound mail using the mailx command, but I can neither receive mail or send mail ...
4
votes
1answer
9k views

smtp remote host responds “550 Sender verify failed”

A server I'm taking care of uses qmail for MTA. I can send and receive to almost every domain except one or two that give the following error, or something very similar: 550-Verification failed for ...
4
votes
3answers
2k views

Sendmail : ignore local delivery

I've a Ubuntu webserver with Sendmail as my MTA Currently when i email outside my webserver's domain e.g. example.com to something like gmail or any other email outside the example.com domain it ...
4
votes
2answers
5k views

SMTP 552 4.3.1 Session size exceeds fixed maximum session size

I'm having a frustrating problem with one of our clients who is running an exchange SMTP server. I have an emailing component that is written in .net and I've specifically used Mono DLL's to ensure ...
4
votes
2answers
667 views

Intermediate SMTP server (exim), how to handle backscatter?

I have a dedicated Ubuntu Lucid box at a hosting provider that is my backup MX (running exim4 4.71-3ubuntu1.4) for domains that I have configured on an Exchange 2007 server on my LAN. So my Exim ...
4
votes
1answer
231 views

Simple, forwarding-only MTA?

I have a domain and a server. I’d like to have some e-mail addresses on the domain and I’d like to forward them elsewhere. I’d love to avoid running a full-featured MTA on the server, since they’re ...
4
votes
1answer
1k views

postfix misconfigured: “mail for (domain) loops back to myself”

I've just installed postfix on my debian system, so I have a default configuration, apart from the following values in /etc/postfix/main.cf: myhostname = mydomain.com alias_maps = hash:/etc/aliases ...
4
votes
1answer
10k views

How to set exim4 to send email anywhere but only from authorised users?

Struggling to get my head around the various relaying controls in the exim4 config. I can send email from my server, I can send email from home and work (because I explicitly added suitable netblocks ...
4
votes
1answer
3k views

How can I configure Exim to drop non-authenticated connections on alternate SMTP port?

I currently only allow connections on port 25 from a mail filtering service's IPs. I have Exim running on an alternate port for SMTP submission. This port needs to allow non-encrypted connections ...
4
votes
1answer
179 views

Hot/Lukewarm mail server setup

We have two mailservers ("dubone" and "dubdeuce"), one does all the work while the other sits idle. We want to have a setup where if dubone is busy or down, dubdeuce can accept/reject/filter emails ...
4
votes
2answers
5k views

How to remove the SMTP address for a secondary domain from all Exchange mailboxes?

I have an Exchange server which used to manage multiple SMTP domains; now it only has to manage one. I have already removed the secondary domain from all address policies; I need to remove all SMTP ...
4
votes
1answer
544 views

Is null return path reliable indication of a bounce?

I have a mailbox that receives bounces as well as normal email (the latter includes messages from automated services). I want to filter out the bounces and forward them to another mailbox. Assume I ...
4
votes
1answer
3k views

Load balancing SMTP in a way that doesn't hide the source IP address

I need to load balance SMTP to handle some applications that don't know how to use MX records. I set up a Netscaler using the TCP option on port 25 and now Exchange sees the source IP as that of the ...
4
votes
8answers
12k views

Emails are being rejected by some email providers

I have this asp.net application that sends out emails. The SMTP server is iis6. The emails are being sent on behalf of our application users and they have different domain names. Most of the email ...
4
votes
3answers
889 views

How to limit amount of email sent by postfix to certain domains and control it by using mail header?

Goal I'm looking for a solution to limit rate of e-mails sent to specific e-mail operator (several Top-Level domains, all of them I know) on hourly basis. I also need some way to control the rate on ...
4
votes
2answers
13k views

554 5.7.1 <mail_addr>: Relay access denied centos postfix

I have problem in send mail from postfix in centos I have following setup mail server postfix for sending mail but I am getting error. As in the link I tried following commands telnet localhost ...
4
votes
3answers
742 views

Security Risk involved in disabling SMTP authentication on POP3 Server?

I provide IT Services to a client who, for the longest time in the world, has been using a POP3 server from Network Solutions to handle their email. At this time, I'm introducing the McAfee SaaS ...
4
votes
2answers
479 views

Creating a “fake” open relay to capture non-relayable outgoing mail with postfix

We occasionally have customer-provided servers in our technical support and engineering departments. They're isolated on their own VLAN, with strict firewall rules in place to minimize possible bad ...
4
votes
2answers
3k views

Can't connect to SMTP server

I have trouble connecting to an SMTP server from my PC. I use Debian sid. telnet mail.example.com 25 Trying 12.23.34.45... telnet: Unable to connect to remote host: Connection timed out While from ...
4
votes
4answers
1k views

How to determine if my mail server is configured correctly?

Does anyone know of an online service (similar to the ones that tell you if a site is up or down) that can connect to a specified mail server and perform checks to see if it is configured correctly? ...
4
votes
2answers
2k views

Simple SMTP server which can redirect all mail to single address?

We're in the process of setting up a continuous-integration server (Hudson running on CentOS5), and some of our unit tests will cause email to be sent. We'd like to configure the server so that all ...
4
votes
1answer
11k views

Yahoo Domain Keys setup, getting dkim=permerror (no key)

I'm working on getting DKIM installed on my outgoing mail server, to help my email deliverability to my Yahoo clients (all legit emails, etc, no spamming). I've got DKIM-Signature: and ...
4
votes
1answer
939 views

how do I set up two smtp ports for postfix?

A CentOS 7 server with postfix, dovecot, and mailx needs to accommodate mail being sent through port 465 and received through port 25. What specific syntax and files need to be changed in order to ...
4
votes
2answers
2k views

Are there any SMTP servers that support the SMTPUTF8 extension? [closed]

RFC 5321 limits email addresses to 7 bit US-ASCII encoding. RFC 6531 (a fairly new spec) allows email addresses in SMTP commands and IMF headers to be encoded in UTF-8. This SMTP extension makes ...
4
votes
1answer
337 views

Does DKIM works with subdomains?

ISP's recommend you segment your marketing and transactional emails by using different IPs. I want to start using DKIM, but since DKIM is a domain based reputation system I wonder if signing with the ...
4
votes
6answers
1k views

Dummy SMTP server as a service

I have a Windows Server 2008 machine with IIS installed which is hosting a webapp that is sending some notification mails once-in-a-while. What I'd like to do is to monitor the email sent by the ...
4
votes
2answers
2k views

Using DHCP to push SMTP server addresses to clients

I noticed on the Windows DHCP service there's an option to add SMTP servers to the information provided to DHCP clients. I've never heard of this before, but it sounds useful, especially for when our ...
4
votes
6answers
941 views

How to legitimately work around ISP rate limits

A lot of ISP rate limit the amount of e-mails that is sent from a particular IP address. What is the proper way to get around that rate limit? Our company has an iPhone application that sends many ...
4
votes
3answers
6k views

Trouble with IIS SMTP relaying to Gmail

I appreciate that similar questions have been asked about how to setup SMTP relaying with IIS's virtual SMTP server. However I'm still completely stumped on this problem. Here's the setup: IIS 6.0 ...
4
votes
2answers
4k views

Mac OS X Server (10.5) mail trapped in queue

We've got mail accumulating in our Leopard Server's queue and not sure exactly why. This machine has required little maintenance over the years so I'm hoping someone here spot the obvious and save us ...
4
votes
0answers
72 views

How can I explicitly disable TLS when sending to one specific recipient?

I have a SendMail 8.14 server deployed in the middle of an SMTP workflow (Outbound mail looks like Exchange -> SendMail -> Appliance -> Internet) I have TLS configured for the first three hosts. ...