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

5
votes
3answers
955 views

Exclamation marks being inserted into Emails at approx 1000 character mark

Have a .NET program that uses the System.Net.Main namespace to send an email via SMTP. Its on a customers site so from there it will go via a (series of?) SMTP relay servers before it reaches its ...
5
votes
2answers
1k views

Exchange Server vs. IMAP

I've been using a hosted exchange server environment (dslExtreme) for years. Originally, I used it w/ Outlook, but now that I have a Mac, I use Entourage. I also use my iPhone to connect to my ES ...
5
votes
2answers
1k views

Are two periods allowed in the local-part of an email address?

A third-party email gateway relay is refusing to process a message for an email address we're sending to. The address is in the format of firstname..lastname@recipientdomain.com (note the two ...
5
votes
1answer
297 views

Postfix SMTP sends to localhost, ignores MX records set to Google Apps

I have the MX records for zaltin.com set to the Google Apps domains (aspmx.l.google.com etc.). If an email is sent to kerrick@zaltin.com from most places, it goes to my Google Apps account. However, ...
5
votes
1answer
22k views

How to configure sendmail to send email via GMail (smtp.gmail.com), using port 465 or 587?

I have configures sendmail to send email via my GMail (Google Mail) account, i.e. via smtp.gmail.com, by editing /etc/mail/sendmail.mc and regenerating sendmail.cf: -dnl ...
5
votes
5answers
823 views

SMTP server, SPF records, domainkeys

Recently we have setup a new SMTP server to send newsletters and promotional mails to our registered users. There are 5000 users who will receive newsletters on weekly basis. We are getting bounced ...
5
votes
3answers
8k views

Mailbox unavailable, client does not have permissions to send as this sender - only the first time

Our users can send emails from our ASP.NET Web application on the click of a button. In our testing environment, there is a strange thing going on. The first time the application tries to send the ...
5
votes
1answer
184 views

saslauthd multi instance for postfix smtp authentication

I have mail server Postfix+Saslauth. I configure multiple instance for Postfix: postfix postfix-out and two instances for saslauth: saslauthd saslauthd-out Setting saslauthd is ...
4
votes
8answers
4k views

How do I add outbound only mail service for local tools to a 'minimal' debian system?

I have several servers running applications on debian. Each has the packages it requires for the application, and no more. Currently, none have mail sending capability. However, I would like the ...
4
votes
6answers
524 views

receiving mail during Exchange maintenance?

I was part of a small company, and sometimes we had to bring down our Exchange server to perform maintenance. The majority of mail during the downtime would get redelivered in a timely manner, but ...
4
votes
6answers
566 views

Why is my port 25 so active?

Using netstat -na I notice that I have a lot of connections like tcp 0 0 XXX.XXX.XXX.XXX:25 YYY.YYY.YYY.YYY:13933 ESTABLISHED tcp 0 0 XXX.XXX.XXX.XXX:25 ...
4
votes
2answers
81 views

In SMTP, how does one choose between “Accept than Bounce” vs “Bounce at the edge”?

There seems to be a variety of implementations of SMTP that either immediately reject a message, and others that do an accept, then bounce the message. Operationally, the accept-than-bounce is a ...
4
votes
5answers
4k views

Outgoing only SMTP server

I want to setup an outgoing only SMTP server on Debian, so my Web-applications will be able to send e-mails via it. I don't want to use another hosts because of security and customizability of my own ...
4
votes
3answers
356 views

With regard to anti-spam practices, what exactly does a typical reverse DNS check look for?

My understanding is that a typical reverse DNS lookup will compare the SMTP hostname (provided in the EHLO/HELO command) of an incoming connection and verify that it matches the PTR record for the ...
4
votes
2answers
94 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
2answers
105 views

SMTP allows for multiple FROM addresses in the RFC. Was this ever useful, why does this exist?

SMTP allows for multiple FROM addresses on the body (not the envelope) according to the RFCs. Has this feature ever been used for a legitimate purpose? Is it safe to discard messages that have ...
4
votes
3answers
2k 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
6answers
8k 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
2answers
197 views

What is the difference between 3-digit and dotted SMTP error codes?

When looking up SMTP error codes, I sometimes see "550", or "5.5.0". (And sometimes the number in the dotted code is different.) I found the numeric codes defined in RFC 821 and the dotted codes in ...
4
votes
2answers
1k views

Custom headers in Email lost?

I have some questions about custom mail headers Does anybody know of any mailserver which deletes proprietary/custom headers when being transmitted to its destination? Is there a header you can set ...
4
votes
5answers
10k 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
1answer
1k views

Exim TLS and Secure SMTP

I'm in the process of converting an existing mail server to support encrypted SMTP for our clients, but I've run into this brick wall with very little useful log data to help me forward. Everything ...
4
votes
1answer
171 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
136 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
1k 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
2answers
3k 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
296 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
2answers
1k 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
824 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
4k 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
1answer
422 views

Are there any SMTP servers that support the SMTPUTF8 extension?

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
1k views

SMTP authentication failure + PAM-MySQL cannot authenticate

I am building a mail server using Postfix, and set up the authentication to check against a database set-up using Postfixadmin. I can authenticate via Courier IMAP okay, as it can authenticate ...
4
votes
0answers
1k views

Outlook 2011 (Mac) refuses to send email, error -17092. All other clients work [Solved]

Having spent a while debugging this, I thought I'd post here so others can save some time. The error from Outlook 2011 is: "The SMTP server does not recognize any of the authentication methods ...
4
votes
2answers
4k views

How to read the “MS ForeFront” antispam report in email header?

I'm trying to diagnose why emails I'm sending out from my server's IIS SMTP Pickup Folder are getting bounced back occasionally. One tech from a receiving company who couldn't receive the emails ...
4
votes
3answers
185 views

Exchange 2007 - One server set-up

I'm trying to set up Exchange 2007 with just one server (not the Transport + Hub configuration, just a Hub). I installed the server with the Hub Role, and it's not accepting SMTP. I changed SMTP so ...
3
votes
4answers
4k views

Fastest way to allow sendmail relay through smarthost?

I only want sendmail to relay through my ISP's smtp server, nothing else. How do i set it up?
3
votes
2answers
283 views

How to copy outgoing messages on sendmail

I've searched the serverfault and Google, but did not find anything related to my question yet. So, I have a customer that wants to read all emails sent by his employees. I've configured a VPS with ...
3
votes
1answer
417 views

Flood of traffic on port 25

I am getting thousands of hits on port 25, over 400,000 connections in a day. I am using sendmail default settings on Debian 7. Mailserver is not configured. Please see below Nginx access logs ...
3
votes
6answers
649 views

Monitoring incoming email server

What do people use to monitor that their email server is accepting external email? Most monitoring solutions send notices by email which is useless when incoming email breaks, so some other method of ...
3
votes
2answers
19k 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 ...
3
votes
4answers
4k views

Disable SMTP AUTH on Port 25

Due to PCI-DSS, we are required to disable plaintext authentication. We've achieved this by encapsulating communications between our mail server and clients with TLS on port 465. The problem lies in ...
3
votes
2answers
231 views

Change or spoof outgoing SMTP server name

Having a strange problem here. We send out emails from a web application that use an SMTP server setup on a Windows 2008 R2 server. Everything was working fine but one of our customers changed their ...
3
votes
3answers
1k views

Has anyone used Amazon Simple Email Service (SES) and if so does it have standard SMTP configuration?

We want to use the more advanced features of Amazon SES such as their API for having better control and visibility over emails. However I also want it to work OOB with our current system which is ...
3
votes
3answers
1k views

Unauthorized email is sent using google apps registered domain

I have a domain name 2m.lt registered and added to google apps. There is an option there that all the email adressed to my domain (*@2m.lt) is forwarded to my mail email account (admin@2m.lt). Well ...
3
votes
6answers
2k views

Push email to a apache/php server

We've built a web service that needs to check constantly for email messages. Basically, an user sends us an email, and the server should make actions based on that email. We could use a crontab PHP ...
3
votes
2answers
81 views

SMTP: Which IP should I monitor?

I use a relay server to deliver external mails. I use relay server's IP in SPF record. But I'm not sure about blacklist monitoring/checking. Should I check main server's IP or relay's IP?
3
votes
2answers
5k views

postfix for sending emails thru php?

I want to install postfix (apt-get install postfix) to be able to send email thru php mail(); But i don't get does postfix needs an smtp to send emails or he can do it on his own? (because if it ...
3
votes
3answers
4k views

Multiple PTR records

In your experience, have you found there to be any actual problems with having redundant PTR records (same name, multiple IPs) for a given host? Additionally, would you expect to see corresponding A ...
3
votes
2answers
294 views

How secure is our companies SMTP server if the PHP MAIL function can use it?

My company has just switched from having our e-mail hosted through a web hosting company to hosting it ourselves. I have been using PHP's mail function for forms on our website and because the web ...