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

0
votes
0answers
9 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 ...
0
votes
0answers
18 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 ...
0
votes
0answers
13 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 ...
1
vote
2answers
24 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 ...
0
votes
3answers
34 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 ...
1
vote
0answers
33 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 ...
0
votes
1answer
23 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 ...
0
votes
2answers
42 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 ...
0
votes
2answers
28 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 ...
2
votes
0answers
37 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 ...
0
votes
1answer
13 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 ...
1
vote
2answers
17 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 ...
0
votes
1answer
11 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. ...
0
votes
0answers
18 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 ...
0
votes
1answer
24 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 ...
16
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 ...
1
vote
1answer
26 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
votes
1answer
21 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
54 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
33 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
40 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 ...
0
votes
1answer
22 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
19 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 ...
0
votes
0answers
19 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, ...
0
votes
1answer
17 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 ...
0
votes
0answers
40 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
votes
1answer
40 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 ...
0
votes
0answers
10 views

Sending email through telnet SMTP [migrated]

After I connect to one of gmail's SMTP servers (via windows cmd), when I try sending mail to myself, it keeps giving me the same error. 220 mx.google.com ESMTP u3si16129057wmg.22 - gsmtp ehlo b ...
1
vote
2answers
25 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
13 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 ...
1
vote
2answers
54 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 ...
-2
votes
2answers
69 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, ...
0
votes
2answers
50 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
67 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 ...
1
vote
2answers
57 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 ...
0
votes
0answers
14 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 ...
0
votes
0answers
27 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] ...
0
votes
0answers
15 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 ...
0
votes
1answer
27 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 ...
-1
votes
3answers
33 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
54 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 ...
0
votes
0answers
26 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
57 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
52 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 ...
0
votes
0answers
19 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
33 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
100 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
66 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 ...
-1
votes
1answer
21 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 ...
0
votes
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 ...