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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Should I block the other SMTP ports as well to block outgoing mail?

I have blocked outgoing port 25 to prevent spam being sent from my servers. However, I'm not very familiar with SMTP and I have heard that ports such as 465 and 587 can also be used to send mail, but ...
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11 views

Tripwire unable to send mail

I'm installing Tripwire Enterprise Console (Server) onto a windows server that happens to be an SMTP forwarder. I proceed through the steps to install TEC and it completes not reporting any errors. ...
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0answers
14 views

421 4.3.0 collect: Cannot write … (bfcommit, uid=0, gid=110): No such file or directory [on hold]

There are an issue: i want to use swiftmailer but when i try then the system says: # php yiic.php sendnotifications exception 'Swift_TransportException' with message 'Expected response code 250 ...
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votes
1answer
18 views

List of DNS Queries when webclient tries to connect to a smtp server [closed]

I am trying to understand the DNS queries which are being used by smtp servers and mail client. I am not sure about the webclient queries. Please correct me : SmtpServer trying to connect to another ...
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0answers
56 views

Permission denied in Postfix's smtp authentication

I am trying to install a SMTP server on my personal machine (ubuntu server). I've been reading up on a lot of documentation and decided to try my hand at Postfix using sasldb2 for authentication. The ...
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0answers
18 views

Own company SMTP-server but feasible due to SPAM [closed]

Our company is growing. We want to set up an own e-mail-server. For this reason we are renting a root-server. This root-server has a static ip. This means we have to install a pop3/imap-server on our ...
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1answer
34 views

How can I disable sending mail through postfix smtp with out auth

I just setup a mail server with postfix 2.6.6 and dovecot. I have the auth related config in main.cf like below: smtpd_tls_cert_file=/etc/httpd/ssl/mail.crt ...
-1
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0answers
25 views

apache james mail server load balancing

I have a apache james 2.3.2 server setup in a windows server. Mail server works fine and able to send and receive mails. Also able to see the mails in respective mail directories in that server. Now I ...
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1answer
24 views

Configure Citadel to be Used For sending email using smtp

Sorry for this foolish question, but I have less knowldge about servers. So bear with me! I have configured Citadel as directed in linode documentation and can login using the front-end for accessing ...
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1answer
38 views

Sending mail from PHP gives Unrouteable address

I have a Debian server running PHP and Exim4 (among other things of course). The PHP application is sending 1000s of emails every day all of which work fine, however I now have a new customer and my ...
0
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1answer
14 views

Using IIS smtp for incoming and outgoing and use hMailserver for mail accounts

I have installed hMailServer in one machine and IIS STMP in another machine. Even though hMailSever itself is a SMTP server. I can't avoid this because the IIS SMTP server has some hooks which which ...
2
votes
1answer
32 views

What does an empty AUTH EHLO SMTP response mean with MS Exchange?

I'm a programmer, not a sys-admin, but my customer's sys-admins are not being helpful and after much googling I still can't find the answer to this. My Java application gets the following response ...
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2answers
47 views

If I use postfix for mail relay, so is myhostname / mydestination important?

I use postfix to relay mail to 3rd party SMTP and never sent out email directly, and of course I never receive email. So If I set myhostname / mydestination to sth like fake.mydomain.com, which ...
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1answer
53 views

Email sent from my new server, being suspended by SMTP because “weird” hostname?

I have some problems sending emails from my server: I've been banned/suspended for abuse (IP blocked) by the SMTP server. This happens only on my new virtual server. Right to the question: is my new ...
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0answers
17 views

SMTP - Apache SOLR - Localhost to Server

I'm developing a single page application (ajax-php-mysql) using XAMPP (localhost). The app needs to be able to send out quite a few emails per day, not anything crazy like 100,000 but I do suspect it ...
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3answers
89 views

Is blocking SMTP ports prevent server from sending emails?

I have a Centos server with cPanel on it. Yesterday, some hackers had successfully connected to my smpt server and sent thousand of emails from it. What I want to do is blocking every ports except ...
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0answers
26 views

SMTP Postfix server probably used as a spam relay : how to protect? [duplicate]

I'm using my own mail server to send and receive emails : a Debian 6.0.7 running Postfix 2.7.1 and Courier. Today, I'm suspecting that this server is used as a SMTP relay for spammers... The clues are ...
0
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1answer
35 views

smtp relay attack on our mail server (not an open relay server)

Help, We put our Exchange Server (10.0.0.125) behind a SMTP Proxy server (Xeams if you have heard of it), however recently our client complaints we replies their email too late - and we found ...
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1answer
64 views

Random synchronization error on SMTP server

We can send mails across the network from 1 server to another via a centralized smtp server. However, the we get a synchronization error on the server randomly. So for example if we send a simple ...
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1answer
56 views

SMTPD restrictions

i'm looking for a bit of advice on Postfix restrictions configuration. I'm looking for a balanced configuration which properly rejects spam and unauthorized access retries. Lately, i've been reading ...
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votes
2answers
59 views

Google blocks authentication attempts by my machine to transfer outgoing mails [closed]

I am using gmail as SMTP server (via ssmtp mail transfer agent in Ubuntu 12.04) for sending outgoing mails from my server. But the problem is that Google often blocks authentication attempts by my ...
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1answer
33 views

Postfix does not reject wrong client and HELO name

I have a postfix server configured with reject_unknown_client_hostname and reject_unknown_helo_hostname. Regardless the server accepts non sasl_authenticated connections from clients and HELO names ...
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0answers
37 views

SPF record validation is pass but email is rejected by server [duplicate]

I have SMTP on a windows 2008 server with IIS6. The SPF recored is passed when I send emails to hotmail or gmail but it gets rejected on other servers claiming that there is problems with the SPF. ...
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0answers
23 views

SMTP Connection disconnecting after “STARTTLS”

We're having issues with our mail server. Basically some emails from external networks are not being accepted by the mailserver. After some debugging using telnet and looking through the logfiles, it ...
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1answer
45 views

change ehlo name of Amavis

Server: Ubuntu 12.04 64 bit Setup Postfix + Dovecot + Amavis with Mysql for Virtual domains. I have configured the postfix mailserver successfully. However when I test the Email with mail-tester.com, ...
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2answers
53 views

How to stop or prevent Postfix / smtpd / Sasl brute forcing

There are numerous attempts to connect to my mail server in order to send mail either unauthenticated or to guess username and password to, I suppose, accomplish the same. Should I fight against ...
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1answer
18 views

What is the correct way to get an NDR to be sent when a bounce back occurs?

I have a user who developed a WebApp that sends SMTP messages. Users are able to reply to the message using a MUA (outlook, whatever) but there is no NDR if the user doesn't exist. I suspect that ...
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0answers
80 views

Office 365: 'client smtp submission' suddenly starts failing. How to diagnose client auth error?

Since a few days, my application fails sending SMTP email. The app is in fact a scheduled task (which is running on my local machine, written in C#, using SmtpClient) and occasionally needs to send ...
2
votes
1answer
54 views

How easy is it to sniff the SMTP port of webserver to capture mails

I've got a very basic question that I don't know the answer for. Our company owns a webserver that runs multiple websites and works as a mail server for these websites as well (e.g. to send contact ...
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votes
1answer
38 views

SBS 2003; Exchange 2003 can't receive mails without SMTP connection but without POP3 connector [closed]

i hope you can help. I'm losing my mind. I'm not a specialist in SBS but i have a huge problem. I wanted to replace the mircosoft pop3-connector with popcon because i was told that several mails ...
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2answers
59 views

Correct FQDN Setting?

I can see from SMTP logs that some mail is being rejected OutboundConnectionResponse SMTPSVC1 Sxxx - 25 - - 504+:+Helo+command+rejected:+need+fully-qualified+hostname 0 0 69 0 47 SMTP In ...
0
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1answer
58 views

Where does e-mail header “Received: from…” come from? [closed]

I sent myself an e-mail from my server to my gmail account, here is one of the headers (partially redacted): Received: from cpvds3xx.xxx.com (dev1.xxx.com. [209.51.132.xxx]) by mx.google.com ...
6
votes
2answers
241 views

Why is email being delivered normally despite an SPF “hardfail”?

I'm trying to figure out why forged email is being delivered to major email providers (gmail.com, outlook.com) even though email is marked with an SPF hardfail. The email is also delivered to ...
0
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1answer
52 views

hMail delivery queue full with unsuccesfull spam

Since a day or two the mail delivery queue of the hMailServer is exploding because someone is trying to send spam via this server. Though the e-mails aren't successfully sent it fills up the mail ...
0
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1answer
37 views

Is extra “Received by” in mail headers bad and can I remove it?

I use our own VPS web and mail server to send out a newsletter regularly to 50,000 addresses. I am trying to improve deliverability and was looking through some of the thousands of bounce emails. One ...
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votes
1answer
29 views

Scanning server results in warning about STARTTLS [closed]

After scanning our webserver, I've got this message: The remote SMTP service, support the user of the 'STARTTLS' command to switch from a plaintext to an encrypted communications channel. As I ...
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2answers
104 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 ...
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0answers
51 views

Configuring Monit to Send Mail through Office365

I'm trying to configure monit to send emails through Office365. Here's the relevant configuration: set mailserver smtp.office365.com port 587 username "username" password "password" using ...
0
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0answers
30 views

Undeliverable SMTP email not saved to badmail folder using IIS6.0

I am testing my SMTP virtual server hosted in IIS6.0 to verify that when an email cant be delivered and cant be sent back to the sender, then I need to see a copy of the Non Deliver Report in the ...
0
votes
2answers
46 views

Email flagget as spam or rejected by recipient mail server

I have configured smtp service on a windows 2008 server. All the emails sent by the smtp service are flagged as spam or they are rejected by the recipient of the email. In the header of the email I ...
0
votes
1answer
56 views

Using alternate server for specific subdomain - DNS settings

I'm trying to set up DNS records for a domain name, such that mail.domain.com uses a server that is different from any other request to *.domain.com. As I've been going about trying to figure out how ...
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0answers
402 views

550 5.7.1 Message Rejected due to content restrictions

I have a server that for some reason, out of the blue is now having a huge amount of its email being rejected, coming back with 550 5.7.1 NDR's or various derivatives thereof. This just started ...
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0answers
33 views

Handing E-mail Bounce Back in IIS, Setting up SMTP

Our servers send e-mails from @example.com to customers, clients, etc. We use Google Apps for our domain to send and receive additional e-mails from @example.com. Now, we're trying to handle e-mails ...
1
vote
1answer
177 views

Postfix - Host or domain not found

I just installed Postfix on my ubuntu, on a local network. On this network, I have an Exchange Server (using domain mail.example.com). I had a problem sending an email to a local address : ...
0
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0answers
12 views

IIS SMTP deleting messages that failed to send

Windows Server 2008 R2 with IIS 6.0 SMTP I recently ran into a smarthost permission issue where my IIS mail server couldn't forward certain messages to it. Basically, the user authenticated for the ...
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1answer
86 views

Send email through Gmail SMTP to avoid local delivery attempts?

Background We use Google Apps for email with our domain example.com: [ec2-user@example ~]$ dig MX example.com … ;; ANSWER SECTION: example.com. 300 IN MX 1 ...
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1answer
50 views

Restrict SMTP for localhost only

How can we restrict SMTP service to be used on localhost only? Our websites are using localhost SMTP but we do not want any mail clients to use our server on SMTP port. Our server is Windows Server ...
0
votes
2answers
65 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 ...
2
votes
1answer
44 views

Unable to Connect to SMTP Host

I am trying to configure Postfix on CentOS 6 server, and the problem is that I cannot receive mails. I tested it on http://mxtoolbox.com/ and I get an error Unable to Connect to SMTP Host. I check ...
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votes
1answer
56 views

What are the security risks with running an SMTP server? [closed]

I'm running Windows Server 2012 and I would like to set up an SMTP server to work with my hosted websites. I've previously installed various roles on my server which have resulted in exposing security ...