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.

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SMTP daemon on alternate port to capture all messages to single Dovecot mailbox

There's several answers on here about how to configure postfix to redirect all messages to a single mailbox, for development/testing of mail scripts. I'm looking for a variation on this where I open ...
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103 views

How to relay/forward mail from qmail MTA to Google Apps/Gmail?

I want to forward or similarly deliver mail for "user1@example.com" to a Google Apps mail account for "example.com" from the MX primary inbound SMTP server "example.com" (MTA is qmail). I want all ...
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1answer
76 views

How many simultaneous connections does SendMail allow/open when relaying new (and deferred) messages to a common downstream MTA?

I have several Sendmail servers which relay a lot (hundreds of thousands) of journaled emails to a downstream archive repository via SMTP. All of these emails have the same recipient domain (lets ...
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2answers
93 views

what is the correct solution for an offsite mail relay?

I have an onsite Exchange server. For the rare cases in which our onsite Internet connection goes down, I want to setup an offsite inbound email relay server (I believe this is the correct ...
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1answer
65 views

Port Forwarding to OpenVPN connects once then stops connecting

I am attempting to forward the IMAP and SMTP ports from a external IP address (x.x.x.x) to a computer on a private network via an OpenVPN connection (10.8.0.100). I currently have an OpenVPN server ...
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1answer
93 views

Postfix fail sending to any external domain

I have a problem :( When we try to send a mail to external demain by SMTP and Postfix + Courier+ Webmin, In the logs i got an error : Sep 18 10:57:34 MyDomain postfix/error[26300]: 275FF1EEC9B: ...
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1answer
40 views

How can I configure multi domain IMAPS POPS and SMTPs with single SSL Certificate

If I have 3 domains hosted on single linux based mail server that are domain1.com, domain2.com and domain3.com.and I have *.domain1.com signed ssl certificate. Is there way I can use the same single ...
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2answers
223 views

Client can't connect to mail server with SMTP (postfix)

I have a mail server with postfix and dovecot. The mail server is on a VPS. At the moment, I can send/receive mails from the server itself. It seems to work OK. However, I'd like to use my mail ...
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1answer
504 views

What does dis=NONE mean in an email's Authentication-Results header?

The following is from an email I received recently: Authentication-Results: mx.google.com; spf=neutral; dkim=pass header.i=@yahoo.com; dmarc=pass (p=REJECT dis=NONE) ...
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0answers
149 views

sending email using gmail smtp is working when running my project inside visual studio only

I am working on an asp.net mvc5 web application and I have the following action method to send emails using gmail smtp :- [HttpPost] public ActionResult Contact(Contact c) { ...
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225 views

Email transmission delays between Gmail and our server

A few days ago I started setting up a mail server for our company: OS: Debian MTA: Postfix DNS: bind9 Firewall: pfSense Port forwarding for ports 25 and 53 through pfSense for passing on DNS and ...
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1answer
73 views

Domain does not resolve - error message from receiving MTA

For the first time in my life, I am the owner of an "unsupported" dedicated server, hosted in Europe, I am in Zimbabwe. I transferred various domains from a VPS to this new server, apparently pretty ...
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38 views

Two ips rotating each time an email is sent - iptables

I have two ips attempting to rotate each time an email is sent from server. The following commands say they are configured: sudo ifup venet0:0 ifup: interface venet0:0 already configured sudo ifup ...
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1answer
97 views

Dynamically limit postfix attachment size

For a project I am currently working on, we received a requirement for a 'dynamic' mail attachment size limit. For postfix (which we currently use) this would be easily implemented using the ...
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1answer
33 views

IIS SMTP to create emails as file

Is it possible to configure IIS SMTP to receive emails from client and store into a file? Yes? How? My company does not allow email communication on our secure domain (long story). So in order to ...
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1answer
75 views

Axigen SMTP Server - Disabling 550 Error Messages

I was performing some SPAM Testing on an Axigen Server, when I discovered a flaw which I would like to know if it can be disabled. On the System I was testing, the Server will spit out 550 Error ...
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1answer
40 views

Risk of compromised Amazon SES SMTP Credentials?

I host www.foo.com for a client. The website sends emails via postfix which has my Amazon SES SMTP Credentials configured and my SES has foo.com as a verified domain and this all works fine. Now ...
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1answer
371 views

DNS Setting for POP3 and SMTP email [closed]

I'm new to server configuration, I have used rented webservers a lot, but I tried venturing myself with a VPS to run my own web/email server. All is good, I installed VestaCP to help me with dealing ...
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3answers
615 views

What is the sendEmail equivalent on CentOS 7?

I am trying to follow the steps below. But there is no sendEmail on CentOS 7. I have looked at a few alternatives like Postfix, but I am not sure of the script commands. Alternatively you can use ...
4
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3answers
410 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 ...
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votes
2answers
30 views

okay to allow any outgoing port for sending mail

I have a small app on my centos6.6 server i am running that allows the user to send an email on a custom port and I am allowing any port to be used. Is there any security risk for allowing this app to ...
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1answer
117 views

Exchange 2013 Receive Connector Scoping and Open Relay

I have an Exchange 2013 server which was a victim of spam infiltration, and the exchange server was being used as an open relay for unauthorized users (and domains) to remotely send spam. I have done ...
3
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1answer
89 views

Postfix: Fall back on SMTP relay that has internet access

I have a scenario where I have: Postfix server M (Stores mail) Postfix Server A (Relays mail using internet connection IA) Postfix Server B (Relays mail using internet connection IB) Internal DNS ...
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1answer
162 views

Exim4 server setup and configuration with remote SMTP

I am trying to setup exim4 server with remote SMTP server. Here is my configuration for Exim4. dc_eximconfig_configtype='smarthost' dc_other_hostnames='test.com' dc_local_interfaces='127.0.0.1;' ...
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1answer
345 views

PFsense postfix troubleshooting - SMTP headers [closed]

I am trying to setup google as mail relay but running into some troubles. I get an error that 550-5.1.1 The email account that you tried to reach does not exist My custom main in pfsense looks ...
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1answer
1k views

Mail Delivery Failure - Reason: 571 Delivery not authorized, message refused

Good Morning, We have changed our external IP Address of our mail server earlier this week and ever since we are getting bounce backs from email addresses we can normally send to. One of the error ...
2
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2answers
179 views

Postfix seems to send spam

I recently discovered this in my postfix-log: Aug 4 11:09:12 mail postfix/smtpd[71597]: connect from unknown[59.88.35.206] Aug 4 11:09:14 mail postfix/smtpd[71597]: Anonymous TLS connection ...
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1answer
30 views

java - how to limit sending email by 3rd party tools?

I have a (Win2008 R2) box running the Jenkins continuous integration server. It's a java program running as a Windows service. The command line looks like this: > "C:\Program Files ...
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0answers
186 views

Certificate rejected by Exchange (SubjectMismatch Chain Validation) works with openssl s_client

I am trying to establish a TLS connection between Exchange 2013 and a non-Windows SMTP server. An internal Windows CA was used to generate the certificates for Exchange and the SMTP server. The SMTP ...
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0answers
10 views

SPAM suspected - Internal relayed E-Mails from SAP over Exchange fail frequently [duplicate]

our SAP system is running on UX. Through some transactions, users are able to send out E-Mails to external customers. The UX system sends the e-mail via standard SMTP to our internal Exchange Relay ...
0
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1answer
373 views

Connection refused by [127.0.0.1]

I am not very good with email servers. Here is what I need: I have a mailbox at fastmail.com with my custom domain (let's call it example.com). Now I want to set up my web server to relay emails ...
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2answers
88 views

Is smart hosting to an A record a violation of RFC-5321 section 1?

I have a sendmail server configured to smarthost to a downstream resource. The configuration is currently: define(`SMART_HOST',`relay:[vip.example.local]')dnl Since it's sending the A record for ...
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2answers
127 views

Postfix sender acces restriction - Security breach?

We encounter security problems with our mail server and would like some advice. The story behind it On our mail server (Postfix 2.9.6 + Dovecot 2.1.7) we would like to be able to create restricted ...
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0answers
87 views

mailjet with brimir (open source Ruby project) on debian doesn't send mail

I tired of searching a tip to be able to send mails with mailjet on my debian. I configured a dashboard for tickets (Brimir, Ruby open source plateform) Here is the link : ...
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2answers
404 views

google compute enging postfix relay through gmail

I would like to send directly through gmail, since we have google apps and use gmail as our domain email. I would like to get rid of sendgrid so I can possibly not be marked as spam. I found this ...
6
votes
1answer
53 views

How Does Low Volume Affect (esp. live.com) Email Deliverability?

I've been sending emails for years with out any serious reputational shocks, but with low IP volumes (no bulk mail or automated transactional email), even with multiple Domain names. My Gmail ...
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2answers
225 views

smtp blues - external emails works, internal does not

I have 3 domains hosted on a remote server, but I am using other postfix server for SMTP only. So, I have two servers: mail.domain1.com - remote mail server, storing mailboxes and used for IMAP ...
0
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1answer
48 views

How to configure exim4 to orelay email from a specific IP?

I am attempting to set up an SMTP relay server, using exim4. However, I have only one IP that I want to be allowed to send email through my server. Is this done using iptables or some configuration ...
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2answers
767 views

postfix authenticate disable smtp port 25, but 587

I am trying to make postfix not to auth users on port 25 but only on 587 and using STARTTLS. I have tried may different confs, but no success so far. main.cf: ... smtpd_sasl_auth_enable ...
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0answers
172 views

IPTables, route specific port through VPN

I'm running my own mail server at home on a dynamic IP. Dynamic IPs are often blacklisted, so I currently send out mails through my provider's relay. I want to change that to sending mail directly, ...
1
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1answer
49 views

postfix SMTP outgoing gateway server, Software RAID1 vs RAID1 + RAID 0 on 2 disks

I have this old smtp server that is currently running Windows 2003 and with EOL I want to move it to something that will continue to get security upgrades but at same time I want to improve ...
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0answers
22 views

Postfix SMTP authentication FROM [duplicate]

I have a Postfix server with authentication running. However I recently found out, that anyone authenticated may send mail from any account. Meaning user1 is logging in and may send the e-mail from ...
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0answers
283 views

Exchange sending QUIT after 220 ESMTP Status Ready

I am hoping someone can help with an issue we are experiencing between our smart host and our Exchange 2010 Server. When our smart host tries to deliver email to our exchange, we are met with a 451 ...
0
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1answer
123 views

Why don't I receive the emails forwarded by Postfix?

My desired Postfix configuration is to forward all incoming mails according to virtual aliases and be able to send outgoing mails via SMTP and TLS. Sending already works, but the forwarding does not. ...
1
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1answer
195 views

IIS/SMTP - Disable SSLv2 [duplicate]

I am trying to disable SSL2 on our IIS/SMTP server. We are using a Windows Server 2008 R2 Enterprise (64bit). We use the IIS6 Manager to manage the SMTP virtual servers. I have attempted numerous ...
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1answer
1k views

postfix/smtpd lost connection after AUTH from <server>[ip]

I try to send mail from a private LAN server to my private postfix server and I get this error, but I can't find its meanning: # /var/log/mail.log Jul 8 15:02:50 mail-srv postfix/smtpd[18222]: ...
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32 views

Windows Smtp Server administrator login

I newly setup Windows SMTP Server on Windows Server 2012 R2. Any account exception Administrator can send email. But in the case of Administrator account, mail server said "535 5.7.3 Authentication ...
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1answer
582 views

Implications of removing session size limit from SMTP Virtual Server

I am running into an issue in one of our applications whereby our SMTP server rejects mail: System.Net.Mail.SmtpException: Exceeded storage allocation. The server response was: 4.3.1 Session size ...
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1answer
194 views

Sending an email to multiple recipients via a mail relay, while hiding the recipients

Our software sends emails using Exchange. Typically each email foes to multiple recipients and we just send one email with multiple "to" addresses. We're moving to an SMTP-based email relay, where we ...
0
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1answer
483 views

How to add allowed relay IPs for Windows SMTP using command line or script

I have a long list of IP addresses I need to add as allowed relays to the built-in SMTP service on Windows Server 2008 R2 (IIS 7.5, but SMTP uses the old IIS 6.0 manager) I know how to add allowed ...