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Email Servers





Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. A MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP). The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.

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The user reads their email on Mac, using Safari, and by going to gmail.com

On January 8, the user asked their assistant to help them get rid of all the spam and unsolicited email in their inbox.  

As soon as they looked in the Inbox, they noticed that there were only 350 or so messages in the Inbox, where they recall that there is normally over 8000. There are no more messages prior to November 2017. On that same day, they looked on  Google for gmail support, and reached a company that claimed that they could retrieve 3800 emails for them if they gave them my their card number.  The user was suspicious and didn't do this.  

Today, January 13, I was looking with them.  We went into Gmail settings and displayed the trash folder.  There were not a lot of deleted messages.  When we show ALL MAIL, more shows up, but the count includes only 350 for the inbox, and the rest appears to be normal sent mail.  

The user definitely is missing thousands of past emails.

How can we get these back?

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Is there a ELI5 (explain like I'm 5) for this process?  I'm not looking for a software recommendation.

I searched offline storage table (OST) and read that it "is an offline Outlook Data File used by Microsoft Exchange Server that enables users to work with their messages and mail data even when access to the mail server isn't available."  I also read a lot of content about OST and PST software.

Why would a person work with their messages and mail data even when they can't access a server?  What kind of work is a person doing that this is even necessary to do offline?
When we get a suspicious email, we make a copy of the headers and then look for questionable email addresses and ip addresses in the route.  If we find something we think is a spam source, we block the incoming email address and ip address as needed.  Now I'm questioning that practice.

Here's why.  If you look at the portion of the header below, the email went through a server named VULTR-GUEST.local at ip  Checking the ip, it's registered to a server in Frankfurt Germany - not what we expect.  BUT, my question is, it left that server and went through a couple more registered to outlook.com (Office365 I assume) before finally delivered to our mail server.  

Does it matter that the path took it through that German server, or is the last server before delivery to our system the only one we need to look at and be concerned about?

Here's a little of the middle portion of the header:
(2603:10b6:405:39::24) with Microsoft SMTP Server (version=TLS1_2,
cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.20.407.1 via Frontend
Transport; Wed, 10 Jan 2018 20:43:08 +0000
Received: from NAM03-BY2-obe.outbound.protection.outlook.com ( by
BY2NAM05FT032.mail.protection.outlook.com ( with Microsoft
SMTP Server (version=TLS1_2, cipher=TLS_RSA_WITH_AES_256_GCM_SHA384) id
15.20.345.12 via Frontend Transport; Wed, 10 Jan 2018 20:43:07 +0000
Received: from VULTR-GUEST.local ( by

I deleted some of users from Exchange server 2013 and still found the size of DB as the same.

How to clear the DB and free some space.
We are migrating from in house Exchange 2007 to Office 365. Our VB based order management app uses SMTP to send emails to customers. Instead of doing a ton of recoding to use a new SSL local component, are there any issues with just setting up a local SMTP relay to Office 365? If we have the local SMTP relay server, than we can stick with port 25 and non-ssl.  The relay would send SSL however to the Office365 SMTP server.

Environment is Windows Server 2008 R2, which the VB based app runs on.
Hi Guys,

We have a couple of mailboxes on Exchange, divided into two sites.
The SSL and AutoDiscover settings for both sites are exactly the same.

Recently the one site started using a new internet domain name.
We added the domain to the Exchange server list of accepted domains and added a new reply address to each user mailbox in Exchange of site 2.

All worked well, except the users of site 2 are now receiving a message in Outlook:
"Allow this website to configure mailbox.newdomain.com server settings?

It wants to redirect the AutoDiscover config to the hosting company of the new domain, which has nothing to do with our Exchange server.  Mail for the new domain is already being delivered to our Exchange server.

AutoDiscover and other settings should stay exactly the same.
i am relaying emails from my server to thru my ISP, which has been working except just recently routine text emails have been bouncing

the service log bounce error

Jan  6 11:31:01 culser postfix/smtp[14808]: E10DE19C627: to=<@gmail.com>, relay=smtp.rcn.com[ unknownip ]:25, delay=0.57, delays=0.02/0.01/0.37/0.17, dsn=5.7.1, status=bounced (host smtp.rcn.com[] said: 554 5.7.1 [P4] Message blocked due to spam content in the message. (in reply to end of DATA command))

I am running Debian Linux, and using Postfix email transport.
i have the main.cf file attached

I had a simular issue a few months back posted on this site.

please advise
[DKIM] Your DKIM signature is missing.
The message was not signed. This means that the message had no DKIM signature. This is not the same as failing.

What is the cause of this error?

I can say, I host the image file as my email signature as a domain that does not match my email's domain.

Is this the problem?

On a related note, what is the SPAM impact of hosting my email signature image on a domain that does not match my email's domain?

I would love that since I could send a dozen different emails, and use that to improve my odds of being blocked.

It's a great service is anyone as looking for a new business, in the event the service does not yet exist.

I suspect my email may be flagged as SPAM and need to understand if so, and how to fix it.

I use a CRM call PipeDrive. This has two ways of tracking emails...

1) When the recipient has viewed the email, I get an alert.

2) In the case the email also contained a web URL, I get an alert when that URL has been clicked.

3) I also use an email signature as an image file, hosted by a web development company of mine.

Did I describe anything that makes my emails SPAMMY?

I see huge swaths of emails I sent that never got opened, but more directly, a customer I spoke with today had not gotten my emails.

When I sent a bare bones email, it got through.

Is have an image file (my signature) in the body of the email a red flag for SPAM filters?

What about the tracking mechanism for:
1) email's been read
2) the URL's been clicked.

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I use several third party softwares, to allow them to email on my domain's behalf I have to add records to my domain.
The problem I have is that two are trying to use the same host:

Host: s1._domainkey.mydomain.pro
Data:  XXX

The domain manager won't let me add the second because there is an existing one with the same 'host' information.
How can I add both using the same Host info ?
Given that SSL is no longer considered safe due to the POODLE vulnerability, what email options exist?


And does this POODLE vulnerability actually expose someone who sends an email with a secure PDF as an attachment?

Is there a way to securely send an email with a merchant's credit card monthly statement as an attachment? If so, what types of email are considered PCI compliant?

If not, other options are there for sending a PDF? DropBox?

What are the alternatives?

I use a CRM which has the nice feature of showing what emails were viewed, and when they were viewed.

Does this exist with ThunderBird? Or is there some other email client I can use that has this?

I had two mailbox server in DAG , today one server is fully crashed but data base is not mounted on second mbx server. Now crashed server is showing service down status and. MBX server which is live, database status is showing Dismounted and unknown
my Submission Queue Length everyday shows 300 to 400 mails which  get an alert from SCOM

is that some thing to do with corrupt mail.que, if s how can I repair it

I have an exchange 2013 box that is running perfectly without any problem.

I also have an mDaemon box that is managing another domain - on a separate Box.

I am trying to setup my mDaemon mailbox to send emails using the SMTP of my exchange box. but it is not working no matter what I try.
Care to help me out ?


PS: The purpose of the operation is to have only 1 gateway to send emails and not 2.

Eventually, I will add the mDaemon domain to my exchange but for now I don't have the green (administrative) go !


 I have SBS2011/Exchange 2010 on a physical server.
 I am considering Hosted Exchange service and like to hear about Pros and Cons from those who migrated to it.
 1. I know mailbox size limitation is 50GB in hosted exchange service. Email archive service is available, but cost extra. On-prem exchange, I know I can let mailbox size grow beyond 50GB.
 2. How does "Setting up Forwarding account to an external email address" work in hosted exchange service? In On-prem exchange, I can create a separate contact person so that incoming email to certain mailbox is forwarded to external email address at no additional cost.
 3. I know that perhaps biggest benefit of hosted exchange is that you don't have to worry about exchange database corruption/repair situation which is overwhelming and time-consuming. I am curious if you don't run into any mailbox or exchange database corruption or problems in hosted exchange environment.
 4. In on-prem exchange, I am free to add or delete user mailbox anytime and anywhere without having to pay for them.
 5. Finally if I decide to keep on-prem exchange service, is there a benefit to upgrade to newer version like Exchange 2016 rather than using Exchagne 2010?

 Thanks for your insight in advance.
Good Evening,

I was unable to receive mail from the internet but can send mail to the internet. I would be very happy if you can help me out. I am studying for the exam 70-341. I really want to understand the practical aspect of the course (how mail flow from external mail to internal mail) and not just to pass the exam

I am testing Exchange Server 2013 using home Lab.

I have static IP address which i use to configure NAT to enable all my VM have direct access to the internet.

I have a domain name and SSL Certificate which i bought from Godaddy.

I have a Edge Server with one (1) NIC which is a member of a Workgroup but using the same gateway IP on my internal network.

I run a test using Microsoft Remote Connectivity Analyzer the Outbound SMTP Email pass the test successfully but the Inbound SMTP Email test Fail. The Outlook Connectivity also fail the test.

The result of both test is attached for your view.

Hi All

Im wondering if anyone has had the same scenario and whether they have a workable solution.  

If someone sends an inbound email to my company with an attachment that is too large for my receive connectors we wont know that its been rejected.  What we would ideally like is for either the recipient or the external sender to be sent an alert to tell them that their message has been rejected, and the reason being is that their attachment is over our accepted limit.


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lot of emails are getting stuck in submission queue length lately  on our exchange 2010 dag server

is there any reason we need to look

like Retry Remote Delivery Queue Length-7008
Aggregate Delivery Queue Length (All Queues)
Statistic      5618
Hi ,

I have a got few certificates .
1. "Microsoft Exchange Server Auth certificate" ,
2.Microsoft Exchange.
3.Exchange Delegation Federation.
 certificates which are  going to expire soon on CAS SERVER 1,CAS SERVER 2,MAILBOX SERVER 1 & MAILBOX SERVER 2 of my exchange server 2013 Enterprise in DAG . How do i renew the Certificate or do these certificates really required?

Thanks in adavance,
I just setup DMARC reports on my domain.
Now I am getting reports. One for example says the following:

This is a spf/dkim authentication-failure report for an email message received from IP on Fri, 15 Dec 2017 01:02:42 +0800.
Below is some detail information about this message:
 1. SPF-authenticated Identifiers: none;  2. DKIM-authenticated Identifiers: none;  3. DMARC Mechanism Check Result: Identifier non-aligned, DMARC mechanism check failures;

Emails are being randomly generated with addresses that do not exist like "434321@mydomain.com".

What do I do now? I obviously do not want these to be sent. They should be stopped I their tracks.

Here is my DMARC record:

v=DMARC1; p=none; rua=mailto:dmarc@mydomain.com; ruf=mailto:dmarc@mydomain.com; sp=none; ri=86400

Do I need to do anything?????
Newbie at this.
My organization has Server 2016 Active Directory sync with Office 365 in the cloud.

User's Office 365 email addresses use the same Server 2016 Active Directory passwords that are used to logon to the user's computers.

Some of the users are remote and don't have Active Directory joined computers.

Are there any ways for users to change their Office 365 email addresses using Outlook Web App (OWA) or other methods?

In the past I have tried changing user's email addresses within OWA but haven't been able to do so.

Are there any settings or changes that need to be made to allow this?
How can I delay when an email is sent using Outlook Web App (OWA) for an Office 365 user?
Users cannot search emails in Outlook.  Or it is incredibly slow.  Tried resetting indexer on exchange already but does nothing.

Email Servers





Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. A MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP). The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.

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