Following Problem: I have written a mailing-list via PHP, SwiftMailer and Postfix. On my Old server it worked without any problems, but Since I moved to another Server (Exactly same configuration, but other IP) the list-mails stuck in the Spamfilter of the Receivers. (Espacially in Google Mail)
Is there anything I have to do escept rerouting the URL DNS-Records, that Google sees, that "I am that Server" and the mail is no spam?
First, check that your outgoing mail server is identifying itself correctly in the HELO command (or EHLO command) when it connects to a receiving mail server. There should also be an A record for this name that should point to the IP address of the mail server. Also, this IP address should reverse to some name (possibly, but not necessarily, the same name as above), and this name should point to the mail server's IP. If any of this is not right, then most spam filters will not consider your server to be a 'real' mail server, and will most likely flag any message sent from your server as spam. This is how many spam filters block spam that originates from computers that have been taken over as 'zombies'.
Another thing to do is to check that you mail server IP is not on any blacklists. You can use MXToolbox for this: http://mxtoolbox.com/blacklists.aspx
Another thing you can do is use port25's verifier tool. This tool will spot any red flags that might be causing your messages to be flagged as spam. See http://www.port25.com/support/authentication-center/email-verification/ for more info.
Last but not least, you might want to setup an SPF record for the domain that you are sending these messages from, to indicate that the IP of your mail server is authorized to send mail from this domain. This will help a lot. For more info, see: www.openspf.org.
Related
Honestly, I think I have a fundamental gap in understanding how SMTP works. I can't seem to find a good explanation of what is happening behind the scenes and I think this is preventing me from being able to do what I am attempting to do.
To explain, I'm trying to setup an application which sends notifications to users by connecting to an SMTP server. Fair enough. I figure, since I'm using my own domain, I have SPF/DKIM/DMARC configured, I can add an MX record for the host I set the application up on (my SPF record has the mx keyword to authorize any hosts in my MX records to send/receive mails). Then, I can have that same host run a super lightweight SMTP server that can accept mails from the application, and send them on to recipients.
Almost crucially, I want this server to basically just run on localhost so that only this application can connect and send mails through it, but so that it can't really "receive" mails sent to my domain (I have set the MX priority very low (well, a high number) for this app server). I figure since I'm running my own SMTP server, that I don't really need to authenticate against it (it's running on localhost), just take in any mail and send it on to recipient domains.
When sending on to recipient domains... does the SMTP server need to authenticate to say, the gmail SMTP server as a user in order to send mails over there? That seems weird, since it's not a user logging into gmail to send mails, it's an SMTP server that is authorized within SPF sending mail from my domain (From address from my domain as well) to where ever the app server user's email is based (in this example, the user would be e.g., some_user#gmail.com).
I tried using python's aiosmtpd command-line and telnet to send a mail from test#MY_DOMAIN.TLD to test#MY_DOMAIN.TLD and it didn't seem to deliver the message; I figured aiosmtpd would connect to the preferred MX servers for my domain (my "real" MX's) to transfer the message, which would then put it in my inbox. That didn't seem to be the case, and I'm not sure why.
Exact repro steps, where example.com is my domain, and terminals are running on a box with a hostname listed in my MX records.
Terminal A:
$ aiosmtpd -n
Terminal B:
$ telnet localhost 8025
EHLO <example.com>
MAIL FROM: test#example.com
RCPT TO: test#example.com
DATA
FROM: Application Notifications <test#example.com>
TO: User Name <test#example.com>
SUBJECT: App Notify Test
This is a test!
.
QUIT
How do SMTP servers normally send mail between each other? Do they each get some login to each other's SMTP servers to authenticate with, and since I'm not doing that, this is a problem? Can I run a SMTP server on localhost and have it send mail out of the network without receiving mails (a no-reply service)? Is there something obvious that I'm just missing here that solves all my problems?
Thanks
It sounds like you want to run a mail transfer agent (MTA) that relays email to remote SMTP servers. An MTA will typically act as an SMTP server to receive messages, and then it will act as an SMTP client when it relays the messages to remote hosts.
MTAs generally operate in two different modes: (1) They will relay messages from authenticated users to remote hosts, and (2) they will receive messages from remote hosts to its users and store them somehow. The combination of those two modes - where the MTA will accept messages from remote hosts and relay them to different remote hosts - is called an open relay and is sure to attract spammers and place your server on spam blacklists.
aiosmtpd is not an MTA or an email relay out of the box - it is merely an SMTP server that will receive messages and do whatever with the messages you program it to do. By default it will do nothing - that is, it will receive the messages and throw them away. If you want to implement an email relay in aiosmtpd, then you need to implement the SMTP client portion of the MTA, e.g. by implementing an aiosmtpd handler that instantiates smtplib.SMTP to connect to remote hosts.
However, if all you want is an email relay, then you most likely don't need aiosmtpd at all - postfix is probably a better choice.
aiosmtpd can be a good choice if you need to implement mailing list software or perform some automation tasks based on incoming emails from e.g. cameras or scanners.
If you want to implement an email relay in aiosmtpd, then you need to ensure that both the software and your server are configured in a way that you don't relay unauthenticated messages from the outside internet.
See also: Python aiosmtpd - what is missing for an Mail-Transfer-Agent (MTA)?
So, I actually figured out what was missing here.
I need to run an SMTP server, yes, but I also needed to write code to parse the "to" domain (the recipient domain), perform a DNS request for the MX server(s) of the recipient domain, and then use the smtplib client to then send mail over to the recipient domain. Authentication is not needed to relay that message to the recipient server, authentication is only required for reading from a given inbox or authenticating a sender to send on behalf of a domain (I trust myself and myself only to send mail). I can do all this while also only listening for mail on localhost so that only my local server can use the local SMTP server for relaying messages/emails off to recipient domains.
Additionally, I don't need to have my external IP listed as an MX server since it's not accepting mail for the domain, only sending. I do need an SPF record for it though so that it is an authorized relay/sender for email from my domain.
I have a Coldfusion page (CF10) that creates a report and sends it via cfmail to a list of recipients. The ones in our internal domain are receiving, but the external addresses are not.
I found a couple threads where people were having the exact same problem, and the solution was to add the CF server's IP address to the Exchange server. So our IT guys did just that - they added the IP addresses of all of our production servers to the receive connector on the Exchange server. However, the mails are still not being relayed, and I'm continuing to get the same message in the mail log:
javax.mail.SendFailedException: Invalid Addresses; nested exception is: com.sun.mail.smtp.SMTPAddressFailedException: 550 5.7.1 Unable to relay
I'm not familiar with everything that needs to happen to make the Exchange Server relay email to external addresses. Adding the IP addresses to the receive connector obviously isn't enough. Are there other steps that need to be performed?
Coordinate with your IT guys. Write a ColdFusion page that they can run that sends mail to an external address they can access. Then tell them to do what they have to do to receive mail at that address.
Solution was simple - we originally specified the mail server in the cfadmin mail settings, but included no username/password. That worked fine, until we wanted to start sending cfmails to addresses outside of our own domain. So IT created a dedicated "Noreply" account for this purpose, and I entered the username/password in the cfadmin mail settings.
I've been trying to install a Postfix server for handling mail for my domain. I found some nice tutorial and I was able to create email address and server responds correctly with telnet (imap and pop3 included, I also charge the config in Gmail and works correctly).
To handle POP3 and IMAP I have installed Courier
The problem comes when I try to send e-mails to myself (with external email address), I receive the following error code:
Action: failed
Status: 5.4.6
Diagnostic-Code: X-Postfix; mail for (servername) loops back to
myself
I reviewed my postfix mail.conf config, as in many webs they said that it could be because mydestination was not corectly configured. I have included the domain configuration and I still get the same error. (/etc/postfix/main.cf)
mydestination = mail.mydomain.com, domain.com, localhost
This is in a VPS, so the hostname is different to the domain name, I'm not sure if this can have any influence on the handling mail error.
Could someone help me to find where can the error be?
Thanks for your attention and your answers
You're probably sending mail to a recipient, with an email address in a zone which has an MX record, with its value a hostname, which resolves to the ip address of your mailserver, while this your server hasn't been told in its main.cf config file (behind mydestination), that it is referring to itself.
Therefore, your server is wondering why an attempt to send mail to - as it believes - another server results in finding that the ip address of that another server is its own ip address.
Update mydestination accordingly.
It helps to use the same hostname for MX record, for all zones your mailserver handles incoming mail for, as that keeps your mydestination manageable.
I've recently setup my Ubuntu web server with exim4 so my PHP website applications can send email such as "thank you" and "confirmation" notices.
I've got it setup and working such that I can send email to gmail, Yahoo! and my work address. However, my work email gets caught up in our spam filter. I'm new to setting up mail servers so I'm not sure what I might need to look for in making this mail server more trusted, while keeping is secure.
Here are some details:
Server is NATed behind a firewall.
Firewall has port 25 open for outgoing SMTP traffic (from server to anywhere).
Server is virtual hosting a couple different of our websites
The server is running the following exim4 config:
dc_eximconfig_configtype='internet'
dc_other_hostnames='web-serv.example1.com;example2.com'
dc_local_interfacees='127.0.0.1'
dc_readhost=''
dc_relay_domains=''
dc_minimaldns='false'
dc_relay_nets='' dc_smarthost=''
CFILEMODE='644'
dc_use_split_config='false'
Questions:
Do I need to open port 25 to incoming SMTP mail (anywhere to server)? I wonder if other mail servers need to talk to my mail server to verify itself, in a sort of handshake attempt.
I have not created any MX records primarily because the server has different websites on it the mail server should send mail for all the websites. Do I need to pick/create a domain address and create MX records for it?
One thing of note is that the mail headers look like this:
Return-Path: <www-data#example2.com>
Received: from web-serv.example1.com ([Firewall public IP Address])
Received-SPF: neutral (google.com: [Firewall public IP Address] is neither permitted nor denied by best guess record for domain of www-data#example2.com)
"web-serv" is the host name of the server, such that you get this if you type it into the command line:
$ hostname
web-serv
and "www-data" is the account name for the Apache2 server that Ubuntu gave it as default.
Any other general advice would be appreciated. It's all new to me.
Cheers!
One item of note, since I posted this question time time ago (almost 10 months) is that I found out the biggest issue I had was with setting up the DNS for reverse DNS on our hosting providers side of things.
In other words, our hosting provider (the people who give us our IP address and manage our hardware) had to enter a record to match my server(s) hostname to whatever IP address it used.
There's a specific name for this. I believe it's a "PTR" record but the name escapes me at the moment, but you basically tell them "my server hostname is ..." and they do a quick update to the DNS for reverse DNS purposes.
When I asked this question, we had a different hosting provider who didn't really help explain this to me, and after switching providers, I got to talk to someone who was happy to help me understand that side of the equation.
And as I understand it, this is setup by the people who assign you the IP addresses. But there's probably more to it than that.
Once I got that setup properly, email had no problem getting through the spam filters and Gmail/Yahoo showed SPF as "passed". It was showing neutral before.
Our company email was set to drop any email that would not resolve reverse DNS, which is why I could not even receive the email or find it in the spam filter. Of course, that situation would be dependent on the company and what email policy and software they're using to manage spam. Some might just drop all email that does not reverse DNS and some might dump it in to spam filters instead.
Hope that might help some people with similar issues.
Cheers!
I want to write some email scanning software and don't understand how to setup my server. I have a hosted web server running Windows 2003 Server. It is running the Default SMTP Virtual Server with a fully-qualified domain name of abcdef.com (example). DNS is pointing abcdef.com to my server. If I spoof an email from my desktop pc so that it appears to come from info#abcdef.com, and I send the email to a 'non-existant' email address then the bounceback does arrive on my web server and is stored in C:\inetpub\mailroot\Queue on the server - great! (I can scan it and handle the bounceback). However, if I simply send an email straight to info#abcdef.com then it does not seem to get placed anywhere on the server. I don't understand why bouncebacks get stored but other incoming email doesn't. I'm keen to avoid having to install any 'email server software' on the server, as I want to keep things as clean as possible. All I really want is some way of telling the server to accept all incoming messages to abcdef.com so that I can process them myself, and to place the .eml files in a known directory that I can scan. I'll then write an eml file parser to process the files.
Thanks very much.
A possible reason for the lack of delivery is that your domain has a DNS A record, but no DNS MX record. MX records are used for delivery of mail. Historically, if no MX record was present for a domain, mail servers were supposed to fall back to looking for a domain's A record.
In your case, I'd guess that your local mail-sending software is looking for an MX record and then stopping if it doesn't find one, whereas the remote system sending you the bounce is looking for the MX record and then looking for an A record when it can't find one.
The Wikipedia article on MX records has more details.
SMTP is a message transfer agent (MTA), responsible only for handling the transfer of mail from one point (the client, perhaps) to another (the mailbox server, such as a POP or IMAP server). SMTP servers aren't the right tool for ultimately handling mail coming INTO a domain -- they only handle transferring the mail coming into a domain to another app, such as the aforementioned POP or IMAP server, which then know how to sort and store that mail.
In short, the Default SMTP Virtual Server isn't the tool you're looking for for your project.
From this other StackOverflow question, it looks like there are a few SMTP servers which are intended for development use but which might serve the purpose you seek -- they accept incoming messages and then write them to files (in some manner, and with some tweaking).
Ok, working now. Issues were as follows:
There was no MX record, so external email wasn't being directed to the server. The .EML file that existed on the server was indeed placed there by an outbound email process.
The firewall was blocking port 25 - now opened.
It is necessary to have some sort of inbound email service running on the server. Windows Server has a lightweight POP3 service which you can configure to place all incoming email into a single 'catch-all' mailbox. This fills with .EML files, which can then be scanned by our custom service.
Many thanks to delfuego & Jon.