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To Email - Tools for email
Here you will find many useful online applications for working with e-mail. We are actively developing and updating all features of this site, so we will be glad to hear your feedback. If you need an application to email that you did not find on this site, we can also add it for free in the future, only leave a extensive explanation of what you need. We are also looking for new methods fight with spam that come to email and all features of this site are free.
mailserver  email  spam  sysadmin  sendmail 
19 hours ago by dusko
What do you do when you find out that you are the spammer? | IAS Security
Which brings us to Cisco's Talos Intelligence (https://talosintelligence.com/reputation_center), AKA senderbase.org. Cisco has thousands of devices around the Internet looking at inbound email. Then users click on the spam button in their browsers. If enough users click and they see enough spam, they will downgrade your reputation on the Internet. Anyone using a Cisco IronPort or similar device will start blocking your inbound email. Cisco has told me that they base their reputation score on some ratio between number of complaints and volume of "good" email that they see from the ip address in question to change your rating. The scale goes between -10 and 10, but their public website will only tell you "poor", "neutral" or "good".
----

What can I do?

Well, the easiest thing is to change the IP address of your mail server. This allows your business to keep running while you try to sort out your mail issues. This will help with the majority of RBLs, but it wouldn't help at all with Cisco Talos Intelligence (AKA senderbase). To get a better reputation with them, they have to see legitimate mail coming out of your server. Of course, if that email is being blocked by major vendors/schools using IronPort, then what do you do? You could get fancy and route those emails over a new fresh and shiny IP that isn't compromised, and all the rest of the old IP to get it polished back up.
mailserver  email  spam  sysadmin 
9 days ago by dusko
Open Source Threat Intelligence Feeds - SENKI
The community of open source threat intelligence feeds has grown over time. We have new sources being offered all the time. Many companies offer freemium services to entice the usage of their paid services. There are community projects which aggregate data from new sources of threat intelligence. We also have an emerging market of companies who pull all this and other data into Threat Intelligence solutions. Finally, there are security companies who offer their threat intelligence as a community service. The result is a massive amount of information. The following is maintained for the participants of the Operator’s Security Toolkit program.

The following list of open source threat intelligence feeds is maintained for the participants of the Operator’s Security Toolkit program. It provides a list of the resources, activities, groups, and organizations. The links and data can be used in many ways. The most obvious is to “check the credibility” of any security vendor that claims “special security data” and then offer it to the Operator at a special price. We have found cases where people have taken open source community data provided for the best interest of the Internet and then sold it to governments who paid a huge sum. This resource is one tool to prevent this type of abuse.

Note – This one of several lists of open source threat intelligence and security data source list. At the end of this document, you will find links to other sources. It is recommended that people seeking open source threat intel, security, and other data sets review all list to find the “hidden nuggets.” It is the experience of the editor that broad explorations yield the best results.
mailserver  sysadmin  spam  security 
9 days ago by dusko
FraudGuard.io
FraudGuard is a service designed to provide an easy way to validate usage by continuously collecting and analyzing real-time internet traffic. Utilizing just a few simple API endpoints we make integration as simple as possible and return data such as: Risk Level, Threat Type, Geo Location, etc. Super fast, super simple.
mailserver  spam 
9 days ago by dusko
OBM - a free messaging and collaboration platform
We are not just talking of a scalable infrastructure, thousands and thousands of users on the same infrastructure...

Access your enterprise from everywhere

OBM is a free messaging and collaboration platform useful for just a couple to many thousands of users with strong support for mobile devices.

Try our live demonstration server

Install it on your own GNU/Linux server

Ask Linagora for a paid SaaS account

OBM is Free

OBM is free as in speech and free as in beer.

No license cost, no freemium offer, everything under your control.
OBM is ubiquitous

Make your content available both offline and online, synchronizing with thunderbird and your mobile phone and providing a sexy web access.

OBM aims to provide well-integrated groupware and project management for teams of all sizes. In today's fast-paced world, high availability is a must. Therefore OBM provides a secure solution that reduces the chance for an outage. As Linagora's focus is on Open Source Software, OBM uses the power of the community to provide a premier quality solution fit for the users needs.

OBM is scalable

OBM will grow with your organization, regardless of its size.
mailserver  server  sysadmin 
17 days ago by dusko
The Horde Project
Horde gives you the ability to access your information no matter where you are – On the road using your mobile phone; at your desk with our powerful browser-based interface; in the datacenter linking all your business systems together. The flexibility to get the right information to the right people at the right time.
mailserver  sendmail  mta  smtp  web  opensource  imap 
18 days ago by dusko
Sendmail Basic Configuration - Webmin Documentation
Configuring Domains to Receive Mail For

By default, Sendmail is not configured to receive mail for any host or network other than the machine on which it is running. So you must first configure Sendmail to permit anyone to send mail for delivery to your domain through your server. Open the Local Domains page, and enter the domains for which your server will accept mail. In my case, I would enter swelltech.com. Any number of domains can be entered here, as can host names, so I could also enter www.swelltech.com if ever I expected mail to be delivered to that address.

Click the Save button to update the sendmail.cf file. This will add new Cw lines to include your specified domains.
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Permitting Local Users to Relay

The next step to achieving a simple mail server is to permit your local users to send mail through your server. Click on the Spam Control icon, and create one or more rules matching your local networks. To create a new rule, first select a Mail source of Network, and specify the IP of the network you'd like to relay for. For example, on a local network using private IP addresses, one might enter 192.168.1 to specify all of the hosts in the 192.168.1.0/24 network. Then, select Allow relaying, and click Create to add the new rule to the access file.

Finally, return to the primary Sendmail page, and click the Start Sendmail button. It is usually useful to keep an eye on the logs when starting a daemon so that problems will be immediately obvious. Sendmail logs to the maillog on most systems, which is likely located in /var/log directory. You can use the Webmin System Logs module to view this log.
sendmail  mailserver  mta  smtp  sysadmin 
19 days ago by dusko
Virtualmin - Mail server virtual hosting control panel
Virtualmin is a powerful and flexible web hosting control panel for Linux and BSD systems. Available in an Open Source community-supported version, and a more feature-filled version with premium support, Virtualmin is the cost-effective and comprehensive solution to virtual web hosting management. And, Virtualmin is the most popular and most comprehensive Open Source control panel with over 100,000 installations worldwide.
sendmail  mailserver  mta  smtp  cloud  sysadmin 
19 days ago by dusko
Using a Homespool - sendmail
In a standard mailbox configuration, every user has their own inbox file which is stored in a central mail "spool" directory (traditionally /var/spool/mail or /var/mail). In a large cluster of machines, this complicates administration, because disk space, NFS servers, and quota management all have to be done twice: once for the home directories and again for the mail spool.

As a result, many large installations use a "homespool" setup instead. This means that each user's inbox is stored in a file in their home directory instead of in a seperate spool area. Different sites use different names for this file; I usually call it .INBOX.

Since sendmail doesn't access the user's inbox itself, no modifications to it are necessary to move to a homespool scheme. What you do need to change are your local MDA and all of your MUAs. They all access the inbox directly, and therefore need to be modified to know where it lives.

I have supplied some patches and information on how to do this to some common programs. Please be aware, however, that these patches are not all tested. Use them at your own risk.

Here's how to modify the common local MDAs to use a homespool:
MDA -- Modification/Patch
procmail: procmail-homespool-patch (https://web.archive.org/web/20040830183725/http://www.feep.net:80/sendmail/homespool/procmail-homespool-patch)
mail.local: mail.local-homespool-patch (https://web.archive.org/web/20040830184146/http://www.feep.net:80/sendmail/homespool/mail.local-homespool-patch)

Here's how to modify some common MUAs to use a homespool:
MUA -- Modification/Patch
mutt: Pass the option --with-homespool=.INBOX to configure.
elm: elm.homedir.patch (https://web.archive.org/web/20040830072917/http://www.feep.net:80/sendmail/homespool/elm.homedir.patch)
pine Make sure to set $MAIL (see below) and put this line in the global pine.conf file:

inbox-path=$MAIL

It is highly recommended that you set the $MAIL environment variable to point to ${HOME}/.INBOX when each user logs in, so that unmodified programs which are smart enough to check $MAIL will do the right thing.
sendmail  mailserver  smtp  mta  unix  sysadmin 
19 days ago by dusko
Sample sendmail Configurations: standalone.mc
Sample sendmail Configurations: standalone.mc

standalone.mc

Here are the features of this configuration:

Enforces some recommended security restrictions, such as only allowing root to see the mail queue and restricting message size to 10MB to prevent mail bombs
Uses procmail as local MDA
Supports /etc/mail/access Access Control Database

Here's what you'll need to do to use this .mc file:

Uncomment the appropriate OSTYPE() macro for your platform.
Make any necessary modifications before you generate the .cf file.
Optionally, create the /etc/mail/access Access Control Database using makemap.
Install procmail. Make sure it's configured and installed as a local MDA (it may need to be setuid).
sendmail  mailserver 
19 days ago by dusko
SpamHelp.org SMTP Open Relay Test
This is a SMTP open relay test script which is able to optionally report open relays to DSBL (Distributed Server Boycott List) (http://www.dsbl.org/). Should you discover any bugs or problems, kindly let us know. Please do not abuse the system.
sendmail  mailserver  smtp  spam  mta 
19 days ago by dusko
Open Source Email | Sendmail Sentrion| Proofpoint
The Sentrion platform is specifically designed for large, complex environments, but we make a subset of that solution available as an open source offering. Sentrion is not for everyone, but if you are using open source for a large complex environment and need an enterprise platform that will enable your messaging roadmap for years to come (virtualization, consolidation, cloud migration, etc.), visit our product page to see if Sendmail Sentrion (https://www.proofpoint.com/us/node/12146) is right for you.
sendmail  mailserver  smtp  mta  opensource 
20 days ago by dusko
SPF Check
Updating SPF records requires visibility. Use this tool to find out which servers are authorized to send email on behalf of a domain.
dmarc  spam  sendmail  mailserver 
20 days ago by dusko
DMARC Check
An accurate DMARC record is an important step in securing your email traffic. Use this tool to check your domain's record and validate that it is up to date with your current policy.
dmarc  spam  sendmail  mailserver 
20 days ago by dusko
SMTPfeed Home Page
SMTPfeed -- SMTP Fast Exploding External Deliverer --
(Updated on August 20, 2003)

What is SMTPfeed?

SMTPfeed is a SMTP delivery agent which is called by sendmail, and it improves time required to complete delivery a message to huge number of recipients. SMTPfeed is effective for delivery of large mailing lists.

SMTPfeed requires the LMTP(RFC2033) feature available since sendmail 8.9. But another hack is also required to make feature of SMTPfeed more effective. The hack is for increase number of recipient dramatically in one SMTP transaction. A patch (3.4W) for the hack is also available.
sendmail  mta  smtp  mailserver 
20 days ago by dusko
Unix Review - Book Review: sendmail, 3rd Edition
sendmail is one of the most deceptive products in the networking universe. On the surface, it seems as if it should be quite simple to configure and send email since it has been around for so long. Beneath the surface, however, I think the service/daemon/tool for allowing this to happen is more robust, configurable, and confusing than any other I know. For that reason, I am not comfortable working on complex email problems without a good reference book by my side.
sendmail  mailserver  mta  smtp  sysadmin 
20 days ago by dusko
Set up Sendmail to host multiple domains
Find out how to configure Sendmail to work on a single machine responsible for more than one domain.
mailserver  sendmail  mta  smtp  dns  networking  sysadmin 
20 days ago by dusko
Virtual Users and Domains with Sendmail on Ubuntu 16.04 – LinuxHostSupport
In this tutorial, we will show you how to configure Sendmail to use a virtual user table that’ll allow us to set up user-specific, domain-wide email aliases with multiple domains on our server.
mailserver  sendmail  mta  smtp  sysadmin 
20 days ago by dusko
Sendmail Virtual Hosting - Webmin Documentation
Virtual hosting is a rather broad term applied to many network services to specify that the server in question provides service to two or more network domains with some degree of separation. Specifically, in the case of a mail server, it means that the mail server will deliver to a unique local user based on the user name and the domain in the to field of the received email. For example, an email to joe@swelltech.com would be treated differently from an email sent to joe@notswelltech.com and would be delivered to a different mailbox.

As with most Open Source software there are many ways to accomplish our goal, but here you'll learn the simplest method provided by Sendmail Mail Server. Configuring Sendmail for virtual mail hosting is a three step process. First, DNS must be appropriately configured for each domain being served including an MX record, as documented in BIND DNS Server. Second, the new domain is added to the Local Domains table. Finally, one or more entries are added to the Address Mapping table. As DNS has its own chapter, and adding an entry to the Local Domains table was covered in the preceding tutorial, you'll only learn the final step here.
sendmail  mailserver  mta  sysadmin 
20 days ago by dusko
Amazon.com: sendmail: Build and Administer sendmail eBook: Bryan Costales, Claus Assmann, George Jansen, Gregory Neil Shapiro: Kindle Store
wombat book must have

January 10, 2010
Format: Paperback

The 'wombat' book. If you are a *NIX Admin and you have a lot of email to process or you have sendmail you *MUST* have this book. Everybody today is using "postfix" because it's easy, but it has issues and it IS NOT the definitive MTA. Sendmail is. If you are a *NIX admin and you have a lot of mail to handle Sendmail will do it all. Have been using Sendmail for 15+ years and nothing else is faster or more robust. This book covers everything about it from how it processes and stores mail to how to wright Left-Hand-Side (LHS) and Right-Hand_side (RHS) rules for mail flow, spam control, and external processing. I work at a company that handles tens of millions of emails messages daily and we use sendmail for everything and we have uptimes in terms of years, not months. We tried postfix and wound up replacing it with sendmail, if accepting email for our nationwide employee email base.
====

'sendmail' is one of those classic O'Reilly books that have undertaken legend status. Now in it's 4th revision, there really isn't much new that can be said about this book. With editions having been released in 1993, 1997, 2002, and now 2007, this book is required reading for anyone that is in charge of mail routing responsibilities at their company. With 26 chapters, 1200+ pages and content that is spot on, this is a must buy for anyone that is using sendmail on a daily basis.

***** HIGHLY RECOMMENDED
====

For years O'Reilly has been the last word in exhaustively explaining Unix utilities, and the first edition of this book goes back to 1993. The reason to upgrade to this fourth edition is that it covers version 8.14 of sendmail, which is now the current release. This new edition looks much like past editions, but it also contains in Appendix B the many improvements of sendmail since the previous edition and in which section of the book you can find each improvement covered.

Even though sendmail is an old program, it is still useful. It is mature, reliable, and scalable. Unfortunately, its ability to be configured for all kinds of uses and users has made it much more complex. Sendmail is capable of transporting mail between a wide variety of machines. Consequently, its configuration file is very flexible, allowing a single binary to be distributed to many machines, where the configuration file can be customized to suit particular needs. This configurability contributes to making sendmail complex. This book does a good job of sorting out just about all of the possibilities and questions you might have.
sendmail  mailserver  reading  book  unix 
20 days ago by dusko
Sendmail.org - Virtual Hosting with Sendmail
Many people and businesses are getting their own domain names these days and wish to receive mail using these domain names. They can pay ISPs for this service, or they can do it themselves. This web page is a guide for the do-it-yourself people, describing how to use sendmail to accomplish virtual e-mail hosting. Some knowledge of sendmail, Un*x administration, and Internet protocols is assumed. The best source of information about sendmail is the book Sendmail, 3rd Edition.
sendmail  mailserver  dns  networking  unix  sysadmin 
20 days ago by dusko
Virtual Users and Domains with Sendmail
The objective of this guide is to enable Sendmail’s virtual user table, which allows us to configure user-specific and domain-wide email aliases for multiple domains. These instructions assume you are using a CentOS virtual server.
sendmail  mailserver  dns  networking  sysadmin 
20 days ago by dusko
Configuring email virtual hosting using sendmail
We can host email services for multiple domains like @domain1.com, @domain2.com, etc. on same email server with single IP address. For this the MX records for all the domains to be hosted on server should point to the IP address of the server. Until DNS MX records are properly set email system will not work.
sendmail  mailserver  networking  dns 
20 days ago by dusko
AUTH Command and its Mechanisms (PLAIN, LOGIN, CRAM-MD5) - SMTP Commands Reference
The AUTH command is an ESMTP command (SMTP service extension) that is used to authenticate the client to the server. The AUTH command sends the clients username and password to the e-mail server. AUTH can be combined with some other keywords as PLAIN, LOGIN, CRAM-MD5 and DIGEST-MD5 (e.g. AUTH LOGIN) to choose an authentication mechanism. The authentication mechanism chooses how to login and which level of security that should be used.

Below are the AUTH PLAIN, AUTH LOGIN and AUTH CRAM-MD5 commands/mechanisms described.

In the SMTP communication examples listed below the letters C and S are used to refer to the client and the server (C = Client, S = Server).
smtp  sendmail  mta  ssl  tls  mailserver  sysadmin 
21 days ago by dusko
Setting up Mail Server - The FreeBSD Forums
If you want to send email out, use your ISP's mail server, or instruct Sendmail to use your ISP's mail server using the SmartHost directive. Sending mail from a listed/known dynamic IP address will cause your email to not be accepted by a large amount of mail servers using spam filters incorporating blacklists like Spamhaus and many others. Receiving email is another thing; there are dynamic DNS providers that can help you keep your MX records updated after an IP change, or you can script an update of your own DNS records if you have access to your zone files. Don't underestimate running a public mail server (incoming or outgoing) nowadays, there's a lot involved.

----

For sending mail through your ISP, see this thread, post #4 and up, for SmartHost'ing. Use 'out.mnsi.net' as the smarthost, and it should work.

If you want to relay mail coming from your LAN, put the IP addresses/range of your LAN in /etc/mail/access with RELAY as the second filed, and run make in /etc/mail. Note, access only supports IP addresses in 'classful form' (123, 123.123, 123.123.123, 123.123.123.123), nothing in between (like 123.123.123.128/25), and no ranges (123.123.123.123-125). See http://www.sendmail.org/documentation/configurationReadme for details.

Use docs at http://www.sendmail.org/documentation/installGuide for further help.

I'm not up to speed with dynamic DNS stuff. There's bound to be stuff in ports for that.
mailserver  sendmail  mta  smtp  sysadmin  freebsd  dns 
23 days ago by dusko
forward-email - ForwardEmail is a free, encrypted, and open-source email forwarding service for custom domains
ForwardEmail is a free, encrypted, and open-source email forwarding service for custom domains. Visit our website to get started.

https://forwardemail.net
mailserver  mta  sendmail  smtp 
24 days ago by dusko
c# - What is the unique identification for emails? - Stack Overflow
There is no guaranteed unique id for emails, the Message-ID is about as close as you come. The best you can actually hope for is unique for the server...and even that depends upon the type of mail server and what it does.
mailserver  mta  smtp  imap  sendmail 
29 days ago by dusko
Unique ID in IMAP protocol
Unique ID in IMAP protocol

RFC 3501 (https://www.limilabs.com/mail/rfc/3501) specification says:

“2.3.1.1. Unique Identifier (UID) Message Attribute

A 32-bit value assigned to each message, which when used with the unique identifier validity value (see below) forms a 64-bit value that MUST NOT refer to any other message in the mailbox (folder) or any subsequent mailbox (folder) with the same name forever. Unique identifiers are assigned in a strictly ascending fashion”

“The unique identifier of a message MUST NOT change during the session, and SHOULD NOT change between sessions.”

“Any change of unique identifiers between sessions MUST be detectable using the UIDVALIDITY mechanism”

“The unique identifier validity value is sent in a UIDVALIDITY response code in an OK untagged response at mailbox (folder) selection time.”
mailserver  imap 
29 days ago by dusko
rfc5322 - Is the "Message ID" Email Header unique for each recipient? - Stack Overflow
According to RFC2822 - Internet Message Format:
the "Message ID should be unique for each instance of the message"; however, the MESSAGE-ID field is considered optional and how the MESSAGE-ID field is created is up to the server.
mailserver  sendmail  mta 
29 days ago by dusko
RFC3501 - INTERNET MESSAGE ACCESS PROTOCOL (IMAP) - VERSION 4rev1
The combination of mailbox name, UIDVALIDITY, and UID must refer to a single immutable message on that server forever.
mailserver  sendmail  imap 
29 days ago by dusko
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