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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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
28 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 ...
17
votes
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

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 ...
-1
votes
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 ...
-1
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 ...
-1
votes
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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votes
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 ...
0
votes
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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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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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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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, ...
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 ...
1
vote
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 ...
1
vote
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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vote
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 ...
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votes
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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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 ...
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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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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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 ...
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0answers
29 views

Mail from sendmail no longer delivered but SMTP does seem to work

On Sendmail (debian) In my mail.log I get the usual xdelay=00:00:00, mailer=relay, pri=120324, relay=foo.bar. [10.100.229.64], dsn=2.0.0, stat=Sent [..] [InternalId=43838731190661, Hostname=foo.bar] ...
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0answers
19 views

How can I customize before-queue milter replies in Postfix?

Currently I use postfix with spamass-milter and clamav-milter as before-queue milters, which both work very well. I reject hundreds of messages a day on my small personal mail server on the basis of a ...
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1answer
32 views

Not able to telnet to port 25 from public network, only private

I have postfix configured with inet_interfaces = all. The following all work: telnet localhost 25 telnet 172.34.56.78 25 # local IP telnet 34.56.78.90 # public IP telnet example.com # domain name ...
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votes
3answers
37 views

What hostname and rDNS should I choose?

What should I set as hostname and rDNS? 1 server 3 domains (domain1.com, domain2.net, domain3.de) 1 mail server for each domain My current settings: /etc/hosts 127.0.0.1 localhost 11.22.33.44 ...
-1
votes
2answers
57 views

Prevent using cleartext passwords in e-mail protocols? [closed]

Checking an older laptop in my possession, I found that all of the POP accounts set up on that device, were sending passwords in clear text when Sending and Receiving (Found this with the assistance ...
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0answers
28 views

Sending failed: Protocol Error while setting up nullmailer

I'm trying to set up nullmailer (1.13) to send to AWS SES and failing. Here are the contents of my remotes file: email-smtp.us-east-1.amazonaws.com smtp --starttls --port=465 --user=AKIA.. --pass=.. ...
0
votes
1answer
67 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 ...
2
votes
1answer
54 views

Use CNAME for SMTP Server

I am working on a project that involves use of a transactional email service (like sendgrid). My question is can we create a CNAME in our domain DNS (i.e. smtp.example.com or client1.example.com) that ...
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0answers
24 views

Courier authdaemon socket missing (exim4)

On my Ubuntu 14.04 server, I'm running Exim4 together with Courier. I tried to configure Exim to use a DNSBL blacklist shortly. Since I rebooted the server, the mail server doesn't work anymore. When ...
0
votes
1answer
43 views

Configuring postfix to work with TLS (mediawiki)

I have a couple of questions regarding postfix config. First of all I need TLS as of the pear smtp plugin mediawiki uses, forces TLS authentication. Will it work on 25? Or what's the advised port? ...
0
votes
1answer
147 views

PHPMailer with SSL - CentOS 6.7 VPS - SMTP ERROR: Failed to connect to server: (0)

I have a CentOS 6.7 VPS and PHPMailer 5.2.14 will not connect to my mail server. I have tried troubleshooting the problem but nothing has solved my issue yet. My PHP is version 5.6.18. The only output ...
0
votes
1answer
83 views

Sonicwall: cannot send email (outlook) and drops connection (google drive)

I will start by saying Im a web developer and my networking knowledge is very limited, please be patient =) . We dont have network/sysad in our company. We are having problem with our connection. We ...
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votes
1answer
23 views

Postfix no longer reciving mail

I installed and configured a mail server with postfix(3.1.0-1)+dovecot(2.2.21) on archlinux(4.4.3-1) in December, and on which in confirmed it to be working, both receiving and sending. About a week ...
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0answers
22 views

Cache status code of rejected relayed mail to immediately block aggressive clients?

A legitimate client relays mail over mail server A to the destination server B. B rejects mail to recipient with status code 554 and the reason "Unknown recipient". Can this rejection be "cached" for ...
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0answers
5 views

Postfix DSN suppress DSN in relaying host

I have following scenario with Delivery Status Notification smtp-client === host1(postfix) === host2 == .. === host_N I would like the smtp-client to receive DSN from host1 (sucess,delay,fail) but ...
0
votes
1answer
65 views

Can't open port

I can't open port 25 and 587. Background information: I am running CentOS 7 with firewalld and httpd. Now I want to run a mailserver. I started with installing postfix. Then I added firewall rules for ...
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0answers
248 views

Using PHPMailer on Hostgator (timeout when try to login into SMTP server)

Solved: The problem was that to use the service through hostgator, for some reason the user must log in using main dsn name and not the SMTP domain name. I was using the simple PHP mail() function to ...
0
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0answers
58 views

/SharePoint/IIS/SMTP - emails are stuck in mailroot/Queue

I'm trying to configure SharePoint outgoing email to send e-mails via SMTP within the IIS pickup directory. Emails are just going into the mailroot/queue folder and stay there. They never actually get ...
0
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0answers
36 views

SMTP eMail to one specific client failing

We have one client with 3 domains and we send regular emails to all 3 of them. Email to these domains were sent succesfully without hitch for a number of year and only recently are failing with ...
0
votes
2answers
67 views

I can send email from outside but not using phpmailer (error 111)

I can send email via my webserver from my computer (using Thunderbird), but not from my website using 'phpmailer'. Oddly enough, when I run 'telnet mail.myserver.com 25' on the server, it says ...
3
votes
2answers
92 views

Postfix sender address rejected / using multiple addresses

I have an email server running Postfix that generally works great. I'm trying to use this server as the SMTP server for outgoing mail in a CRM/Marketing platform installation. I've entered the ...
0
votes
1answer
16 views

Avaya switch - need to block port 25

Situation: In QA-DEV Lab environment I need to block port 25 for the egress traffic on AVAYA ERS5510-48T switch. Question: How do I do it using EDM aka Web Interface? Couldn't find anything in ...
0
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2answers
274 views

Postfix as SMTP server for Gmail. (“Send mail as” google option)

I have a vps on ovh.com runing debian 7. I want to set up my gmail account to send, and recieve mail on (for example) myname@mydomain.com address. I searched google for hours and couldn't find a ...
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2answers
197 views

Why does my server hostname appear in Exim email headers sent from a different domain?

I've had several problems with SMTP emails from my server and domain sent using Exim being blocked by certain other domains, which may have been partly due to certain server settings tripping up ...
0
votes
1answer
78 views

What can I do if an SPF hasn't propagated weeks or months after being changed? How to force SPF to propagate?

I set up a domain, SMTP mailserver etc on a Centos box a few months ago, including PTR records that looked like this: pop PTR XX.XX.XX.XX. www PTR XX.XX.XX.XX. mail PTR XX.XX.XX.XX. Everything ...
0
votes
1answer
152 views

How to have exim on server with multiple domains send each mail from its own domain, not the server hostname?

Suppose I have a VPS with multiple dedicated IP addresses and multiple domains: domain-a.com is on 11.11.11.11, mx is mail.domain-a.com domain-b.com is on 22.22.22.22, mx is mail.domain-b.com ...
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votes
1answer
140 views

Explanation of various smtp error codes bounced by mailservers

I'd like to ask real mailserver administrators from here about some smtp error codes - I take care of some customer's mailing systems, and there is a wide range of server replies, many of them not ...