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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7 views

Postfix : Conditional Header Checks

Here is my SMTP situation. Mail flow is tagged by an online relay provider (!!SPAM!!, !!BULK!!, etc) Mail flow is received by an internal postfix. Transport is configured to relay to our internal ...
-2
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0answers
23 views

How email replies in email clients work? [on hold]

I'm writing a very simple email client for learning purposes. I fetch messages via IMAP, and now I want to programmatically send replies to certain emails. I will use SMTP for this, question is: To ...
0
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1answer
33 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 ...
3
votes
2answers
61 views

Postfix SMTP Relay Configuration Error

For the last day I was searching for solutions for this problem: My postfix(+dovecot) configuration is fully able to receive e-mails and to serve them via IMAP but it fails at accepting them via SMTP ...
1
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1answer
15 views

How to reinject scanned mail into the queue using sendmail

I would like to pass incoming mail using virtual_transport to a transport spamassassin (main.cf: virtual_transport=spamassassin) and then reinject the scanned mail into postfix using sendmail. The ...
0
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0answers
15 views

free smtp server on laptop, mail rely [on hold]

How to set up mail relying from laptop with GNU/Linux to outside world? I want to use different mail clients (mutt, thunderbird, mail command,…). Notebook is connected to different networks, so ...
-1
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0answers
38 views

Differences between Exchange's “default” SMTP certificate and others enabled for SMTP?

I know that: You can enable the SMTP service for multiple certificates in Exchange The last certificate enabled for SMTP becomes the "default SMTP certificate" My question: What are the ...
1
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2answers
32 views

How do I setup a server to send emails after starting (i.e. not meaning as an email server)?

Windows Server 2012 R2 w/ GUI, UPS system I am setting up my first server. It is a Hyper-V host that will host multiple VM servers. The system is on a UPS. When the UPS detects an AC power ...
3
votes
1answer
16 views

Routing SMTP Connections to Different IP Sets with IPTables

I'm trying to set up two different IPs for SMTP that each get routed to two different sets of IPs, with no IPs shared between the two sets. I'm trying this, but it mixes the two sets of IPs so that ...
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 ...
3
votes
3answers
2k views

Exim on Centos - Configuring gmail smtp

I want to set up Exim to send the mails through my gmail (actually my domains google apps). I have added the router, transport and authenticator. Specifically: gmail_route: driver = manualroute ...
5
votes
3answers
75 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 ...
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votes
1answer
31 views

Alternative solution when Port 25 is blocked [closed]

I'm running a web server on my VPS (debian & webmin) for hosting my wordpress website along with others too, i've also tried to setup a mail server (postfix+dovecot) but unfortunately my VPS host ...
2
votes
1answer
270 views

Fetch all Mail from an IMAP server with Postfix to distribute on local IMAP server

The situation: The constellation: We have a managed, dedicated server from a professional provider. We currently have Tobit David.fx server in use within our local network which fetches all E-Mails ...
0
votes
1answer
903 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
votes
1answer
223 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 ...
1
vote
1answer
32 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 ...
0
votes
2answers
142 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 ...
0
votes
3answers
854 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 ...
1
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2answers
27 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 ...
0
votes
1answer
11 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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votes
1answer
26 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
34 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 ...
0
votes
1answer
935 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 ...
5
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 ...
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votes
1answer
44 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 ...
-1
votes
0answers
15 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
67 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 ...
0
votes
1answer
40 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 ...
1
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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 # ...
0
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0answers
10 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
votes
1answer
37 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
42k 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 ...
1
vote
1answer
40 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
140 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. ...
0
votes
0answers
54 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
31 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 ...
-1
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 ...
0
votes
0answers
46 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 ...
0
votes
1answer
820 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 ...
1
vote
1answer
26 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
42 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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votes
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
103k 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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vote
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
87 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 ...
0
votes
2answers
86 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 ...