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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893 views

Windows SMTP Service - Configure Smarthost for Specific Domains over different ports

I have a client that was recently acquired by a company. Their email system now resides on the parent company's network. Currently there is no VPN setup between my client and the parent company. I ...
0
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1answer
220 views

How to override an MX value for a particular domain using a transport_maps but have some form of redundancy

I have a postfix mail server and I want to override an MX value for a particular domain. From my understanding this is can be done by the use of transport_maps ...
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1answer
29 views

Wildcard MX record support?

Let's say I want to start a service where customers get their own subdomain on my domain for email addresses only. I have an A record for mydomain.com and a CNAME for www.mydomain.com If I add a ...
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2answers
139 views

Does an SMTP request contain host header information (or just the IP of the targeted SMTP server)?

We are using an external commercial smtp server for our newsletters (sending them through .NET components), and they offer two smtp URLs - smtp.critsend.com and fast.critsend.com -, and the second one ...
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3answers
838 views

Domino always server fails to send SMTP email at first attempt

In our logs, we find the below: Router: No messages transferred to fakedomain.com (host mx.fakedomain.com) via SMTP: The server is not responding. The server may be down or you may be experiencing ...
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2answers
23 views

Smtp sending via Exchange some mails do not complete but still send - why?

I have an application that sends smtp email via a local Exchange server at a customer. All the email sends ok (it gets to the recipient) but some email gets sent multiple times because my application ...
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1answer
10 views

Exchange 2013 return message for old addresses

In my company there are two kind of smtp address in exchange 2013 recipients: j.deere@mycompany.com (old) john.deere@mycompany.com (new) Now I would like to remove all old addresses (j.deere) but I ...
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1answer
20 views

My server mail going junk in hotmail and yahoo [duplicate]

All my server mails going to spam in hotmail and yahoo. Here is my full mail source. Can any one please help me to sort out this issue ? ...
3
votes
1answer
28 views

How can one configure exim still to reject invalid recipients after an earlier ACL returned “discard”?

For the reasons set out in my earlier question Originating (non-critical) emails from a "less-trusted" host, it unfortunately seems that we must run an SMTP server for the sole purpose of accepting ...
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1answer
917 views

lmtp: connect(backend) failed: Connection refused

A long time ago I'm trying to fix this error but I'm still locked, I appreciate any help :). I detail all that I have and what I am trying to do. I am using Cyrus Murder and apparently everything ...
1
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1answer
3k views

Exchange 2010 SP3: 4.3.1 Insufficient system resources

We have Office 365 with a hybrid deployment. Our on-premise server is relaying email directly out to the web (not via EOP). domain-a.com is an accepted domain on our on-premise server; domain-b.com is ...
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votes
3answers
11k views

Exchange Connector Won't Send to External Domains

I'm a developer trying to get my .Net application to send emails out through our Exchange server. I'm not an Exchange expert so I'll qualify that up front!! We've set up a receive Connector in ...
5
votes
2answers
59 views

What to do if one doesn't want to receive email bounces?

Background—the standards RFC 5321 §4.5.5 states: All other types of messages (i.e., any message which is not required by a Standards-Track RFC to have a null reverse-path) SHOULD be sent with ...
-3
votes
1answer
39 views

How do I set up an MTA to prevent spam relay? [closed]

I'm trying to secure my MTA against relaying spam, and am trying to understand what's involved. For example: Say I send an email using an Yahoo account to a Gmail account. When Yahoo is relaying ...
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votes
0answers
12 views

NDR on all mail send

We have an old SBS 2003 running Exhange 2003. Since Tuesday some people start complaining that mail that they send out bounces back. On Tuesday afternoon almost everybody was affected. On a test that ...
5
votes
1answer
53 views

postfix dovecot disable lmtp

I have 3 servers. 1 MX server with postfix and 2 dovecot servers. MX server receive emails and then serve them through LMTP to specific dovecot server. All mailboxes from same domain are on same ...
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1answer
33 views

Configuring Reverse DNS on Windows Server 2008, can't send email

I run a VPS on a Windows Server 2008 machine, and since I got it in January 2015 everything has been running fine, the server has IIS, DNS, and uses Mailenable for email exchange. I've been running ...
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0answers
27 views

Postfix relay smtp to 2 relayhosts for same domain [duplicate]

have a setup in which Postfix relays mail for a specific domain to another mail server (Exchange) via the usual transport file: # /etc/postfix/main.cf transport_maps = hash:/etc/postfix/transport # ...
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0answers
7 views

Show blocked SMTP connections in Exchange 2010

Currently, I have an anonymous receive connector set up on my Exchange 2010 system that allows from an entire subnet. I'm looking to change this to only allow from specific IPs, but need to know when ...
2
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1answer
35 views

Authentication error connecting to a mail server via openssl in the terminal

I've set up an email server using Postfix and Dovecot and I'm able to send and receive mail using various mail clients but for some reason I get an authentication error when I try to connect via ...
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2answers
1k views

How to share a SMTP domain between MDaemon and Exchange?

I need to setup coexistence between MDaemon (13.0.5) and a Microsoft Exchange system (Office 365); the two systems should share the same SMTP domain, and each one should forward to the other any ...
8
votes
9answers
41k views

IIS/SMTP - emails are stuck in mailroot/Queue

I'm trying to send e-mails via SMTP within the IIS pickup directory. Unfortunately the e-mails are just going into the mailroot/queue folder and stay there. They never actually get sent. Does ...
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1answer
35 views

iptables KVM prerouting SMTP

I have a host machine that has to manage traffic on port 25 and route to port 25 on the KVM machine for postfix deamon like this scheme: WAN --> (25) HOST_MACHINE --> (25) ...
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2answers
135 views

Can't communicate with SMTP server from particular machine

Here is the situation: When I run the following on my local machine, the mail server responds: $ telnet mail.server.com 2525 Trying <mail.server.com IP>... Connected to mail.server.com. ...
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0answers
43 views

ubuntu firewall blocking smtp tasks, port 465 is open

I have been trying to get my Wordpress site able to send emails, and it DOES WORK but only work if I turn off the firewall. I am using UFW. However, I do have port 465 (connecting to gmail) open while ...
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0answers
25 views

OpenVZ - SMTP - telnet - Connection timed out

I have problem with SMTP in my OpenVZ container. I've created OpenVZ container by Proxmox on dedicated server in OVH. This container will be as mail server. So I create on "mother-server" rules to ...
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votes
1answer
35 views

How would get an email server reputation via cli or script?

I am trying to monitor email server reputation via cli or script i.e. https://www.senderbase.org/ I found a way supposedly to do it via dig, but the output appears to be very incorrect. It indicates ...
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0answers
39 views

Major Mail Issue - SMTP Local Server Not Working

My database (MySQL), web server (IIS 8 ) AND SMTP server (IIS 6) are all on the same dedicated server (Windows Server 2012) that I'm honestly renting for a bit of system admin practice. I followed a ...
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1answer
815 views

Postfix enable sending to any domain in the Internet with authentication but no SSL

When I try to send a mail by SMTP and Postfix I got a error "5.7.1 unable to relay". After lot of config changing it worked for me to send email to the same domain as server (to other accounts on ...
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1answer
25 views

How to set the username and password for smtpd in Postfix?

I've set up Postfix as SMTP server by adding this configuration to main.cf: myhostname = foo.com mydomain = foo.com myorigin = $mydomain smtpd_sasl_path = private/auth smtpd_sasl_auth_enable = yes ...
0
votes
2answers
33 views

sendmail: why the error codes from error:nouser and no user differ?

With sendmail 8.14, when there is no user at a given domain, the error that sendmail seems to produce is as follow: 550 5.1.1 <info@example.su>... User unknown However, if you use the ...
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0answers
43 views

Setting up reverse DNS correctly and testing it

I have a mail server which I setup reverse DNS on an Azure service. The IP of the server points back to email.example.com which is what I set it to. I also set my local host name and welcome message ...
9
votes
5answers
102k views

Reverse DNS - how to correctly configure for SMTP delivery

I started a new service and we need to send emails to our customers (new account confirms, etc). My server is known as prod01.bidrodeo.com and resolves to 97.107.134.38 . For reverse DNS, ...
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5answers
13k views

How to find out that SMTP server is in open relay?

I used nmap for network security testing. It found that SMTP server was in open relay. Here is the output: nmap --script smtp-open-relay testwww.confidesk.com PORT STATE SERVICE 25/tcp open ...
2
votes
2answers
67 views

How to set up TLS on hMailServer?

Complete noob here. Please be gentle :) I have a Windows 2008 server, running hMailServer. Right now all my communication is unencrypted. I want to start using TLS. So now I've got myself a SSL ...
3
votes
3answers
5k views

Postfix relay host connection fails: timed out while receiving initial server greeting

I have an Elastix server box that I want to send email notifications of voice mails from. I'd like to send them through our company email (hosted by shared web host provider Bluehost). I have followed ...
2
votes
1answer
5k views

Exchange 2003 mail non-delivery (NDR), spam activity? events 7002 & 7004

Windows Server 2003 Small Business Server SP2 Exchange Version 6.5 (Build 7638.2: Service Pack 2) This network has been neglected and has been having email problems for years and was on many ...
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2answers
76 views

How to enable CentOS 7 to connect to an external SMTP? [closed]

I have a web application deployed in a webserver, running on a CentOS 7. This web application sends e-mails through an external SMTP (in-v3.mailjet.com, port 587). How can I enable CentOS to connect ...
-2
votes
1answer
48 views

Will exchange server receive emails with wrong address [closed]

Say if I sent an email to user@theirdomain.com, the exchange server and the user will receive it, but if I sent an email to fakeuser@theirdomain.com using SMTP client, there will be no fakeuser ...
2
votes
0answers
36 views

nullmailer swaps sender and recipient

I want to send emails from my server through external mail server. So I installed nullmailer as one of simpliest MTA in Debian 7 x32. My /etc/nullmailer/remotes: smtp.example.com smtp ...
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0answers
682 views

Postfix sasl relay host - weird behaviour

Previously I had a relayhost set in postfix to mailhost.zen.co.uk - I don't think it accepts SASL - only TLS. So I though I would try changing to a different relay host. However, the following log ...
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1answer
88 views

Configuring E-mail server to allow review of each outbound email

I want to have a separate person reviewing the style of outbound e-mail correspondence sent by new employees. We have an MS Exchange in our organization, but I can look into any e-mail server system ...
0
votes
2answers
635 views

Postfix: can't send mail from remote client

I'm having issues sending mail from postfix. I believe my conf. is very standard, at the end it was put together from various guides. I'm trying to send mail from remote client (iOS Mail, and Mac OS X ...
0
votes
1answer
104 views

Postfix STARTTLS only on port 25

I want to enable STARTTLS on port 25, but for unknown reasons it only works on port 465. master.cf: smtp inet n - - - - smtpd -o syslog_name=postfix/smtp -o ...
0
votes
2answers
541 views

Mail delivery to not-yet-migrated accounts in O365 staged migration

I'm about 10% through a staged migration from Exchange 2003 on-prem to Office 365's Exchange Online. The question I have is how do the migrated users that are now successfully using Exchange Online ...
0
votes
1answer
56 views

SquirrelMail showing empty inbox. THIS FOLDER IS EMPTY

I have installed postfix, dovecot and squirrelmail. I can send messages and also receive messages. But in Squirrelmail web interface i can see only sent messages it is not showing the mails which are ...
0
votes
1answer
101 views

Getting a [550 5.1.1 Recipient not found] (Can't receive email) with CloudFlare

I'm having troubles with my email account. I'm using GoDaddy's Email service and the domains that are not connected to CloudFlare are operating just fine. The problem comes in with the domains that I ...
1
vote
1answer
914 views

Mailx not sending emails [closed]

Using CentOS 5.6 and trying to send (only) emails to remote boxes. I am on a CentOS client box and trying to send email to my road-runner email account. mailx -s "Some Subject" me@tx.rr.com < ...
1
vote
1answer
26 views

postfix configuration and Received from

Having some trouble here. My server has 3 IP addresses and this is my /etc/hosts: 127.0.0.1 localhost 46.38.235.226 brian.smares.de brian 46.38.238.199 stewie.smares.de stewie 46.38.238.137 ...
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0answers
53 views

CentOS/sendmail = How to prevent emails from getting “defer” when sent from php mail() function? [duplicate]

I am working on a server running on CentOS (goDaddy VPS). I have WHM setup on it. And I am getting a lot of delays in emails being sent from php's mail() function. I am looking at the Email > Mail ...