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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Postfix on Ubuntu tried everything, won't send emails

I'm trying to get postfix set-up on Ubuntu 13.04 but no luck so far. I found a few answers here on ServerFault that didn't work. I re-installed a bunch of times, nothing. This is my first time dealing ...
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1answer
77 views

Secure Email Settings for Email Clients & for PHPMailer

I'm trying to work out how to make my outgoing/incoming email's as secure as I can possibly make them. First of all, my domain has Wildcard OV SSL Certificates, I have copies of the .csr, .crt and ...
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1answer
1k views

New CentOS 7 server - Sending mail from a PHP application

Apologies for the newbie question but i'm hoping someone can provide me with some help/steps. I am in the process of migrating a website from a managed shared hosting account online to a new CentOS 7 ...
2
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1answer
2k views

Configure Citadel to be Used For sending email using smtp

Sorry for this foolish question, but I have less knowldge about servers. So bear with me! I have configured Citadel as directed in linode documentation and can login using the front-end for accessing ...
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3answers
61 views

Setting up an email proxy server?

So i have 4 application servers and each one directly connects to an SMTP server to send out the emails. What I want is to have something in the middle that my servers connect through instead, and ...
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1answer
98 views

Number of issues with postfix, DKIM, and mail getting rejected or bulked

I'm having a number of issues with Postfix and mail sent being rejected or put in the spam/junk folder. I am trying to send emails on behalf of a number of my customers. I've got a postfix server set ...
2
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1answer
57 views

Sending mails from Gmail through my VPS (postfix, dovecot, postfixadmin)

This problem has been bugging me for a long time now and i want it to be fixed. On my VPS I have set up Postfix working correctly with postfixadmin and dovecot. (I can send (by terminal) and receive ...
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0answers
24 views

Cannot connect to postfix from Thunderbird

I have Thunderbird set up with IMAP and SMTP. IMAP (dovecot) works fine but SMTP (postfix) does not work. When I try and send an email via the postfix server I get the following in /var/log/mail.log: ...
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0answers
20 views

Which wireshark output format aligns closest with actual SMTP data?

I have a packet capture of a SMTP session (containing an email with international characters). I'd like to extract the message data from that and try reproducing an issue. When I follow the TCP ...
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0answers
33 views

How to encrypt emails sent from Windows Server 2012 SMTP IIS 6.0

I'm running an SMTP server through IIS 6.0 on my Windows 2012 Server, and would like to make delivery of emails to be encrypted. I have attached an SSL certificate to the server and set Require TLS ...
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2answers
28 views

Telnet windows 2008 vs 2003

I have a mail server using powermta on a windows 2003 server (legacy). If I telnet into that server to test smtp connectivity, it works from other 2003 servers and from my dev machine running windows ...
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2answers
52 views

IIS Smtp server cannot send to hotmail,outlook, etc addresses

I have a SMTP server on a Windows server 2008 R2. It can send messages to all other domains except the ones hosted at Microsoft (hotmail.com,outlook.com, etc). The email messages it cannot send remain ...
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2answers
108 views

Zimbra (postfix) receives email from “my domain” but from external unknown server

I've installed a Zimbra 8.0.7, recently the server have become to deliver emails from accounts that belong to my domain ("example.com") but this mails come from external smtps, for example: 1. the ...
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1answer
40 views

Exchange server 2016 Content Filtering

I have setup an exchange server on premise with at SMTP Relay on our VPS. It works very well, unfortunately I’m a little confused as to where I setup the various permissions for SPAM. All my incoming ...
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2answers
56 views

postfix allow localhost only local users

I have a little problem. I am offering some clients access to my server in order to execute own scripts (of course in their own chroot environment, etc...). The problem which occured today: Some ...
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1answer
66 views

Ubuntu/Postfix not receiving emails from outside

I am trying to configure my Amazon EC2 instance to receive emails with postfix. I tried for hours but I never received an email. If I send email from same server terminal it works. This is working ...
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2answers
1k views

Is an IPv6-only MTA possible yet?

Has anyone had tried to run an IPv6-only SMTP engine? Pretty much everybody with any sense has IPv6 configured for major front-end servers. I was curious if anyone had tried to run an IPv6-only MTA ...
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1answer
30 views

exim4 issues sending mail to gmail

I am trying to send automated emails from my server to my gmail account, so that I can get important notices like when my webserver is not responding, or just some daily statistics. As email sending ...
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2answers
30 views

How do I enable recipient verification in Exchange?

My problem basically boils down to this: Exchange (2016) is accepting mail for non-existent addresses and then later sending out DSNs (delivery status notification) to notify the sender of failure. I ...
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2answers
404 views

IIS 6 SMTP unable to relay messages to Exchange Online

Our company uses Office 365 and our email is hosted on Exchange online; however, we have several applications which are unable to send messages directly to Exchange Online due to various reasons ...
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3answers
15k views

Google SMTP Error: 454 4.7.0 Too many login attempts, please try again later

I discovered that while it was possible to use Gmail/Google Apps as an SMTP server for scripted use, if too many emails were sent I started getting error messages: SMTP Error: 454 4.7.0 Too many ...
3
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2answers
6k views

How to change sendmail fallback behavior if TLS handshake fails?

I have a CentOS 5.x server running sendmail that is failing to negotiate TLS with SOME various recipient servers. I'm looking into it. In the meantime though, I've noticed that sendmail will NOT ...
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1answer
41 views

How to configure postfix with ufw so that my web server can send email but it doesn't act as an open relay?

According to this guide: It is important to secure your server and make sure that Postfix is not configured as an open relay. It links to another guide which suggests using UFW as a firewall. ...
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0answers
27 views

Nullmailer: Unable to resolve host

After installing Ubuntu on my VPS the hostname was Ubuntu-1404-trusty-64-minimal. I changed it to hetzner-backup-1 and rebooted. What I did: I did nano /etc/hosts and added: 127.0.0.1 ...
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1answer
28 views

Postfix/LMTP rewriting username to number 1

I have a frustrating issue with my mail server and i am confused as which part of the configuration is concerned, please note that both postfix and dovecot are configured to fetch configuration from ...
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2answers
458 views

Can't send email on Windows Server 2008 with Mailenable

I've got a VPS running on Windows Server 2008 and I'm using Mailenable as an Email Server for POP3 and SMTP. I've had the VPS since January 2015, its my first time configuring a server by myself, but ...
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1answer
25 views

OpenVPN block SMTP Access Server completely

I've tried almost all iptables rules to block smtp on openvpn server but still clients clients can access remote smtp servers on port 25. I'm using openvpn access server. It's creating two interfaces ...
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3answers
62k views

554 - Sending MTA’s poor reputation

I am running an email server on 77.245.64.44 and have recently started to have problems with remote delivery of emails sent using this server. Only about 5% of recipients are rejecting the emails, but ...
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1answer
26 views

Web App Error After Installing Java on Centos Server

Good day. My web app is programmed in jsp, using some of jQuery and javascript, is on a server with Centos 6.4, the app run its own java 1.7.0 - tomcat 8.0.21 and between its functions, uses ...
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1answer
305 views

Postfix “Connection timed out”

I try to send a few emails, but postfix send only 3 emails every 10-20 min. After that postfix sends 3 emails, I get the error: "Connection timed out". mail.log: Jan 4 12:16:39 mail ...
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1answer
30 views

Outgoing emails not being encrypted

I am using postfix to send email. I have mysql set up to manage domains, accounts, and aliases. I have 3 domains set up. One domain is the primary domain and when sending emails to gmail accounts ...
0
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1answer
33 views

IIS mail server relay mails stuck in queue due to DNS?

Recently our internal SMTP relay server stopped working - or rather, stopped sending emails. It responds to send mail requests, a simple TELNET session shows no errors, but all messages get stuck in ...
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1answer
74 views

Is it possible to send emails to a gmail address WITHOUT using GMail as a relay server?

I've been fighting all day trying to properly configure Postfix to get the emails delivered to GMail addresses I finally got it by using GMail's SMTP as a relay server, sadly that server overrides ...
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votes
1answer
43 views

Mail server with different IP than webserver - getting 554 error

I have a webshop running on a Digital Ocean droplet, while the email inbox for the same domain is running on a different VPS. All of the sudden some of the emails sent by the webshop are being ...
0
votes
1answer
31 views

Javamail using Exchange as relay

I have to fix an "unable to relay". The java server has to send emails to the internet. The java server and the exchange server are in the same network. How I configure properly a receive connector in ...
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2answers
58 views

Port decisions for email setup in 2016 (Ubuntu)

I have a new Ubuntu 14.04 LAMP server with the UFW firewall setup on DigitalOcean. My goal is to add email for use on my phone(iPhone) and laptop(via Roundcube). There is a lot of old information ...
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6answers
5k views

Install SMTP Service on Windows 2003 SP2 without Installation CD?

I need to modify my development environment, a virtual image using Windows 2003 SP2, to install the SMTP service under IIS (6.0). The virtual image is a corporate build, and I do not have access to ...
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0answers
21 views

Workaround 554 5.7.1 Error

I've posted this question some days ago, 554 5.7.1 You are not allowed to connect. sending from postfix Based on the answer I've sent some emails to the admin of the other email server, ...
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0answers
59 views

GitLab on CentOS 7 (not sending email) after applying recommendations

GitLab not sending mails and GitLab email notifications not sending have been attempted with no success. I have an GIT with GitLab as a web management setup. However, ...
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2answers
48 views

Exim: Force email auth for users of local domains

I'm configuring exim4 for virtual users with dovecot and postgresql and I got a problem I cannot resolve, the situation is this: I need that when a 'localdomain' user tries to send a email to another ...
0
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1answer
51 views

Postfix mail server refuses connections from outside mail servers

I have a Postfix server with SMTP listening on port 587 which cannot be reached by outside mail servers like Gmail and hence I receive this Mail Delivery Failure when sending an email from GMail to ...
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3answers
5k views

How to clean up Badmail directory?

I was inherited this server so I'm not yet fully familiar with its setup. However, I noticed that C:\inetpub\mailroot\Badmail\ directory contains ~400,000 files. For now I do not want to delete the ...
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2answers
70 views

Postfix SMTP authentication security hole [duplicate]

I have Postfix running on CentOS 6. Everything is working ok except for a security hole in the smtp. I keep getting spam emails sent from my address to my address. I have checked this out on telnet, ...
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1answer
1k views

What is the proper time delay between sending emails for smtp to not fail on windows server 2008 r2 [closed]

What is the proper time delay between sending emails for SMTP to not fail on Windows Server 2008 R2 machines? For example, if I set a 500ms delay, would it successfully send all emails? My software ...
2
votes
1answer
79 views

Checking SMTP headers for spoofed email (did client authenticate?)

I have been using rackspace email service, and I am finding that rogue emails are seemingly coming from harry@mydomain.com to james@mydomain.com but were never actually sent by that user. As per ...
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0answers
14 views

IIS 6 Sending rules

I need to send all emails out as normal with the condition of gmail.com & gmail.co.uk emails. Which need to go via the google smtp relay service. Is this possible to setup on IIS 6? Basically 2 ...
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2answers
59 views

Business partner's IP in China is blacklisted so cannot email me

A business associate of ours out in China who we have been working with for over 5 years is now struggling to email us in the UK.. he is receiving the following error: Your message to .... was ...
3
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2answers
320 views

Is Sender Policy Framework (SPF) effective in preventing Phishing emails?

As defined in RFC4408, Sender Policy Framework only checks the envelope sender (aka MAIL FROM). The From: header is not being tested. As it is the value of the From: header which is usually displayed ...
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2answers
57 views

postfix - users are geting mail from them self that they did not send

Our company has a mail server configured with postfix/dovecot/amavisd on Ubintu 14.04. The system has been running for a couple of years and it worked fine. Recently some users started complaining ...
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0answers
16 views

IIS 6 using Google relay but stopped getting NDR

I had a working IIS 6 server but I had to add the google relay server as I was having issues with sending to gmail account. The sending side of things seem to be fine now but I'm no longer getting non ...