Email Protocols





Interactions between email servers and clients are governed by email protocols. The three most common email protocols are POP, IMAP and MAPI. Most email software operates under one of these (and many products support more than one).  The correct protocol must be selected, and correctly configured, if you want your email account to work.

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Hello Experts - I have a question about making an MX record change.  We are using Barracuda's email filtering service and they are asking that our MX records be pointed to the following addresses:


Currently both MX1 and MX2 point to individual Barracuda IP addresses.  The records are hosted with Network Solutions.  When I sign in, I navigate to the Advanced DNS section to edit but the form requires a numerical IP address and won't allow me to enter the addresses above.  I feel like I'm missing something here, any ideas?
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Dear Experts

We have hosted CRM application  on-premises which is web-based and every user has email settings to be configured, the email server is on internet and also other integration like SMS(sms service provider is on external network) and third party applications, all these were perfectly working until the recent changes at the gateway level and internal IT policy,  I suggested them may be the crm servers are not allowed to talk to the external network of email server and sms service providers,.
please find the attached error logs captured, and these the crm server is of windows server 2012R2 can you please help on how to test and confirm to them based on test result like the issue of connectivity, is it recommend to telnet from the web-application crm windows server to the destination email server/sms sever provider server with the ports -- is this the right way OR any other way to check and ensure the necessary ports and access at the gate way/firewall is opened or not, please suggest.
I'm try to test that my Exchange 2010 SP3 UP23 is actually offering TLS on incoming SMTP emails. I have a 3rd party cert installed and assigned to the SMTP service. The default receive connector has the correct FQDN (our external MX ) , Authenication is TLS and Permission Group is Anonymous. I test my SMTP using and it says my server does not offer TLS, but in the SMTP receive logs on my server i find the connection and it has 250-StartTLS listed. i have also Telnet to my exchange server and it also does NOT show 250-StartTLS.

what am i missing? why do the server logs say TLS is offered, but the other end doesn't get it?
Exchange is running on WIn Srv 2008R2, fully updated, with TLS 1.0,1.1, and 1.2
I had this question after viewing Out of office message is not working. Auto Reply is not working.

Hi pls let me know how to  remove Deny permission of ExchangeLegacyInterop in ADSIEDIT

Thank you
Hi All
I need some help please.
I have 5 Exchange 2010 SP3 RU 21 servers running on Windows 2008 R2.
On 2 of my servers mail all of a sudden stops flowing to them.
There’s enough free space across all drives.
The servers are virtualized running on top of Hyper-V Server 2012.
Certificates are valid.
Server time is correct.
When I attempt to restart the transport service on the affected server it fails to stop and then you can’t start it again.
Even going via task manager and ended the exe relating to the transport service doesn’t seem to help.
The only thing that restores mail to and from this server is a reboot.
Any ideas?
I can send out message via Telnet fine like
29y.pngbut why I encounter problem in outlook below
30c.pngWhy? What other Email client can be used instead of Outlook?
Dear Experts, we have Exchange server 2016 on Server 2012R2. Can we using Exchange Management Shell to forward emails from a user's mailbox to another's ?

How can we do it? Many thanks!

For example:'s inbox have some emails from, we got a request to forward all emails from in user1's mailbox to
Comcast (Xfinity) is recommending that users move to IMAP for email & I am wondering if there are any downsides to this.
My initial concern is that there will be a ton of duplicates in mailbox at the start, or is that not so?
From what I gather, they have a 10 GB mailbox limit - when it gets near full, would I be able to archive mail to a pst (or any other option)?
Would it be best to start with a new profile?
What about getting everything currently in my pst file into the IMAP folder - would I just open pst file & copy into IMAP folders?
What about phones, ipads, etc - how long till all of that synchs up?
About to do this for a neurotic friend & want to be prepared...

I have an Exchange 2010 server Version 14.03.0399.000 which I believe puts it at Service Pack 3 rollup 21. I just did the rollup last week. This server has been running for years flawlessly until I ran this last rollup. Now for some reason, about 3 times a day the SMTP protocol just stops answering.

I believe I’ve got it narrowed down to something happening with the Microsoft Exchange Transport service. Before SMTP stops working I can restart this service, but after SMTP stops talking I can’t restart it, it just hangs.

If I perform a reboot on the mail server all is fine again for 6 to 8 hours.

Any help would be great
HI Folks,

I wonder are there any experts out there that know how to analyse email header source. One of our clients received a bogus email that appeared to come from one of our staff members email address.. it did not. .. unless his email account was compromised.

I've asked the receive to send me the header of that bad email and they did. I put the message header into a Google Product called "Message Header Analyzer" and the results are attached.

My question: from this is there any way to determine the source of the email? Our domain is So did the come directly from us or is it from another source and just looks like from

Am I making sense here? Any help would sure be appreciated!

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An organization I support needs to have a local Exchange 2016 server setup that will integrate with Office 365.

Please provide me with step-by-step instructions on how to do this.
Good afternoon everyone!

I am performing mailbox migrations in a Hybrid environment!

Why am I having a problem in 3 boxes where I do not change 2013 are they? Archive while performing sync is giving the following error.

This Mailbox has 16GB, but this is being used as a mailbox or several users as members.

Migrated data:
Migration rate:
Error: MigrationPermanentException: The file size 104.8 GB (112,571,089,611 bytes) exceeds the destination quota of 100 GB (107,374,182,400 bytes). The file size 104.8 GB (112,571,089,611 bytes) exceeds the target quota 100 GB (107,374,182,400 bytes).
hostupon shared linux web server

for email

I do not see ALL my sent email unless I log into a browser

on devices (iphone/android/thunderbird) I tried imap and pop

Is this a fault of imap/pop
or is this using an inexpensive webserver
What are the steps on how to setup Open Relay within Office 365?
What are the best free services for sending emails without SMTP authentication?

I need to configure my organization's WSUS server for sending notification emails and would prefer to use a free account that doesn't require SMTP authentication.

What are the best free services for doing this?
What is it within certain Outlook 2016 autocomplete email address entries that can cause emails sent to that email address to bounce (even though the email address is correct)?
, on occasion we have seen malware delivered to a user’s inbox and we would like to be able to pull those messages out.

Is it possible to have a powershell command that could remove these e-mails based on items like the senders e-mail address and subject?

we have mailboxes in office 365 but we have proof point gateway through which incoming and outgoing emails go
An important user within my organization received NDRs while replying to emails sent by someone outside of our organization.

We are using Outlook 2016 and Office 365 as our email server.

However, later on the same day, someone else within our organization was able to reply to the exact same emails and these emails reached the person outside of our organization without any problems.

Neither person sending these emails had any attachments sent as part of these email replies.

Since the person we are emailing outside of our organization is a very important person we can't send any test emails or reply to any existing emails to simply test if this issue has been resolved.

So are there any ways we can simulate sending or replying to an email to this person outside of our organization to see if the original issue with the user within my organization had with sending emails to this outside user has been fixed?
i want to set up DMARC AND DKIM,

I have proof point and mailboxes in offic e365

where do i need to set up in external DNS or any steps defined.

i believe SPF is set up in external DNS
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Different employees at our company have had a problem with a large number of malicious outbound emails sent out from their company email address, causing our email service provider to shut off our service until we reset every account's password.  This has happened 5 times now.  When you look at one of the employee's Outlook programs, you don't see the malicious emails in the sent items, you only see the "bounce back" emails in the inbox, reporting that the email wasn't accepted by the recipient.  Neither McAfee nor Malwarebtyes detects malware on the employee's computer.  How can we figure out how these malicious emails are being sent out using the company's email addresses of our employees?  Could undetected malware be running on some of our computers that gives an outside person email passwords that he/she is using to send malicious emails from our accounts?  Is it more likely that our computers are sending out the malicious emails even though they aren't being logged in the sent items folders?  Could someone be intercepting our unencrypted emails and extracting the email password from them?   We have McAfee Orchestrator and a Fortigate 101E firewall appliance?  Could either of these things be used to troubleshoot the problem?
On a recently upgraded win 7 home to Win 10 home desktop PC, user uses AOL webmail.

says that from some users, when they expect an XLS or DOC /DOCX file(s), they ONLY get a file ending in WDL extension.  That's a text document that has the expected file name - kinda like a packing slip in a box.  But that's all that's attached. Not the expected file, just this packing slip text file with the WDL extension.

I told them to have the sender resend and include me.  But sender is a law firm / concerned with confidentiality (but yet, he's using an AOL address : )

So we set up a gmail account and the sender will send to both the aol and gmail accounts and we'll see if it's a sender issue.

I asked if the sender is a new employee (doesn't know how to send attachments?) - the user said no
Did the sender start using a new email system that includes a link to a secure website to get the attachment - the user said no
Are the files too large? Supposedly no.  There's a number after the file name, supposedly the file size?  in one email, it was 256.  (bytes?  KB?)

Any thoughts on why someone would get a WDL file rather than the actual file?  Yes, there's loads of ways to approach this / try troubleshooting. But getting the sender to send emails / answer questions about what they are using to send, etc. is hard.  so trying to figure things out with limited info.

googling, it doesn;'t come up with anything about attachments / emails.  WDL is some gaming file extension …
Is there a way to limit registration to certain email domains?

//email validation / only allow certain domains to register
      $allowed_domains = array("", "", "");
    $email_domain = array_pop(explode("@", $email));
   if(!in_array($email_domain, $allowed_domains)) {
    //Not an authorized email

this code isn't working, it allows all email addresses to register.
We as soon going to have to migrate off our current SBS 2008 Server. We are using the Exchange Server. The controller is concerned about the cost of moving the emails. $6 /email /month works out to $2880 per year for Office 365 email. For people who use basic email I must agree that is a lot. Are there other reliable options that don't cost as much as Office 365?
My OS is win 10 Prof 64 bit and I use office 365 and Outlook owa for my msn email account.  How do I get educated that the sender of an email is really the sender and not someone else emulating him or her.   As I get so many emails I would like to be educated on this, is there any site or video where I can discern more knowledge.  Thank u and regards.
How to restore my SENT emails in
They disappeared.  I did NOT delete them!!!!! Thousands of them.
I am using the web interface.  I have not downloaded them to my local drive.
I downloaded the email recovery add in but am NOT getting any SENT emails. Just some of my inbox.  is the link I am using even though my email address says "HOTMAIL".
I don't want to recovery any of my INBOX.  Just my sent.  I have thousands  of SENT messages that I need to recover.

Email Protocols





Interactions between email servers and clients are governed by email protocols. The three most common email protocols are POP, IMAP and MAPI. Most email software operates under one of these (and many products support more than one).  The correct protocol must be selected, and correctly configured, if you want your email account to work.