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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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
81 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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2answers
72 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
68 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
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1answer
97 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
218 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
17 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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33 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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23 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
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1answer
39 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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3answers
43 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 ...
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2answers
62 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
42 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
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1answer
99 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
60 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
32 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 ...
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1answer
51 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
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1answer
256 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
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1answer
113 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
24 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
24 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
9 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 ...
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1answer
76 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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454 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 ...
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0answers
103 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 ...
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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
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2answers
91 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
113 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 ...
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1answer
17 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 ...
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2answers
390 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
296 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 ...
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1answer
117 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 ...
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1answer
286 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 domain-...
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1answer
244 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 ...
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2answers
60 views

smtp email forwards with Gmail and Wordpress

I'm looking for help. I'm trying to add a new email account to Gmail. I've done it before for one of my websites email domain and it worked fine. However, now, this is the message I get. Furthermore, ...
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1answer
41 views

MX Record for a physical server

I've a physical server which is used as a Mail Transfer Agent(MTA), I'm using postfix as SMTP server and cyrus as IMAP. I've a static IP for the server and have SSH access to it. Postfix and cyrus ...
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0answers
85 views

Postfix with Dovecot Disconnects after STARTTLS on Port 25

I am having a lot of trouble setting up the Postfix to do STARTTLS. It seems that I could successfully send outgoing mail using Thunderbird. However, I can't seem to get the Postman SMTP for Wordpress ...
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0answers
48 views

Mail subdomain not connecting to Windows Server Virtual SMTP via Telnet Client

I trying to set up subdomain (e.g mail.mydomain.com) for use with a virtual SMTP server running on windows server 2012 SP2. I’ve tried to telnet with the command ‘telnet mail.mydomain.com 25’ but it ...
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1answer
60 views

Exchange 2013, flow messages to a third-party smtp

I plan to use a SMTP Archiving feature in my archiving solution (non Microsoft). I wish to send a BCC copy of every message to a particular SMTP server (installed on archiving software). In Exchange ...
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1answer
141 views

mutt failed to send mail with error "sendmail: Cannot open mail:25

Hi I am trying to send mail using mutt command as below, mutt -s "test" madk@mycompany.com </dev/null This fails with following error, sendmail: Cannot open mail:25 Error sending message, child ...
2
votes
1answer
72 views

Exchange Online, Mandrill, SPF and DKIM

I have a customer ABC Ltd (abc.ie) who has a requirement to send emails via SMTP to their own customer base from within an application that we have developed for them. For their company email they ...
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0answers
305 views

Postfix couldn't send mail on Ubuntu VPS server, network unreachable/connection timeout

I have a problem with postfix. When I am trying to send some mail from commandline, I get: Feb 14 12:44:35 some-server postfix/smtp[1022]: connect to gmail-smtp-in.l.google.com[2a00:1450:4010:c07::1a]...
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2answers
73 views

What's the usual re-sending time period for SMTP servers? [closed]

What I want to ask is about SMTP servers, say, which operate at different IT companies (hosting SMTP servers, corporate SMTP servers etc.) I know that every server can be configured differently, but ...
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0answers
14 views

Which host(s) to include in SPF record to prevent email spoofing [duplicate]

I've got domain name and email hosting from a third-party hosting provider (1and1). Some of the email addresses under the domain are being spoofed by spammers. In order to mitigate this I'd like to ...
2
votes
1answer
56 views

IBM Domino - incoming e-mail loses formatting, no winmail.dat

IBM Domino 9.0.1FP4 HF523, IBM Notes 9.0.1FP5 We have a problem receiving incoming SMTP e-mails from a particular (external) sender that's only recently started, in that all formatting is stripped ...
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0answers
44 views

mail server should anyone be able to send internal mails from external IP without authentication?

Sorry for the long title. My parent organisation that owns the company I work for accepts emails to be sent from test@org.com to test@org.com when connecting via port 25 telnet externally. I'm ...
0
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1answer
43 views

Mail reaches SMTP Server but isn't delivered to Exchange?

I recently setup my own Exchange and SMTP Server on a virtual memberserver. Now if I send a mail (with my .net script) it reaches and passes the SMTP Server but it doesn't show up in my Outlook inbox. ...
1
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1answer
77 views

Best way to combine Google for Work with postfix mail server / e-mail routing

I am re-designing our company mail services, and we are migrating some mail-boxes to Google for Work. The objective is to have some users in the cloud, and some users on an on-premise Postfix server. ...
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1answer
59 views

Exchange - non-received mail return code 5.7.0 Access denied

I am experiencing strange problems on our Exchange servers (exchange 2003 SP2); lately some domains can't communicate with our server. We are able to send messages outside without any problems, but ...
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0answers
27 views

535 error from gsmtp

I am using Erlang and its esmtp library to send emails from my application. It used to work OK and still works fine on the development machine. Unfortunately several weeks ago it stopped working on ...