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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We have a client who has just had a DKIM domainkey setup for them. Unfortunately some emails are not getting through to the end users (especially if using Mimecast mail servers).

We have been doing some testing and have found that:
Emails that do not have an attached file - it pass the DKIM checks.
If emails have attached documents, they seem to pass OK as well.
If emails have got an attached email that was originally from the sender, it passes OK
If an email has an attached email from a third party (that has originally been changed with DKIM) it fails the DKIM test on our/the recipients servers. This has happened to us and we use exchange online servers.

When it fails it says dkim=fail (body hash did not verify)

They have a valid SPF record also setup and every email through the testing procedure seems to pass on the SPF checks without any failures.

There is no DMARC record setup yet, but as far as I can see this is the next step after we have got DKIM working correctly.

Unfortunately our client who is having this problem quite often forward a lot of emails during their working day so need this resolving.

Any help would be appreciated.
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Dear Guys, please assist this scenario:
- Action: We changeed Email server from Gmail to Exchange 2016 On-premise, so we had to change the domain records in Domain control panel. We changed TXT, MX, @, mail records.

- Problem: After changes, the new Exchange server worked (send/receive emails) normally as expected, however we realized that we could still login to Gmail account, Google Drive and sent emails (but could not receive emails)

So can you please explain?

outlook email alerts not coming. How keep alerts so that when email comes popup comes and also preferably some sound comes?
please advise
Dear, I tried but could not start this service. Does anyone get this error before? Can you please help?
Many thanks in advance,
After reboot, I got this error in Exchange Management Console, also I could not login to OWA, it showed blank page when I entered correct username/password.

All Exchange services are running. Environment: Exchange 2016, Window Server 2012R2

Can anyone help, please?
"The Name on the security certificate is invalid or does not match the name of the site"

We have a user who is experiencing this error when traveling . Problem only occurs when connecting to MS Outlook via a hotel or public wifi, but not all of the time.

Similar issue occurred two weeks ago on the same user's cellular phone (as well as a coworker he was traveling with). Both employees were out of state when this happened

  • We have other employees who travel out of state who have reporting nothing
  • We are on Exchange 2010
  • User is on Outlook 2010 client
  • Validated with Godaddy, our certificate issuer that the certificate is perfectly fine
  • Validated with MXToolbox that mail autodiscover resolves fine
  • User connects perfectly fine from home, which is also out of state (remote worker)
  • Issue began two weeks ago, making this problem seem like more than a coincidence

If there's anything else I should be looking at, I'd love to know! TY -Dave
Does Migration Wiz migrate all emails, calendar items, contacts, tasks, etc. from Gmail into Office 365?

Or does it only migrate emails?
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Dear Guys, we are deploying Exchange mail server. We knew that the Mail server must be published with an public IP address (and registered with A, MX, TXT records) but is it mandatory for an Active Directory (of mail users) Server to also have an public IP address and to be registered (by A record) in domain control panel?

Many thanks in advance,
When I email users from one particular company domain (and only that domain) they get my email from my company domain email, but when they reply (and also if they just directly write to me)  it doesn't come to my company email, even though on their outbound email that is what shows as the 'to', instead it arrives in my personal yahoo email, even though the sender couldn't even possibly know what my personal yahoo email is.

This happens for any sender from this particular company to me, but the same doesn't happen when that company sends emails to anyone else in my company, they work fine. They also say they never had this problem with anyone else. I do not have any forwarding of any kind of redirect set up in my email system. None of my other colleagues have any issues receiving emails from this company.

Looking at the header of the message I receive it shows

X-Apparently-To:; Thu, 27 Jul 2017 07:39:28 +0000
Return-Path: <>
Received-SPF: pass (domain of designates 104.4xxxx as permitted sender)

Authentication-Results:; domainkeys=neutral (no sig);; dkim=pass (ok)
Received: from  (EHLO (xxxx)
 by with SMTPS; Thu, 27 Jul 2017 07:39:27 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=selector1-sender-com;

From: Asxxxxx…
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I am having an issue with getting vcenter emails working. Vcenter 6.0. Mail server is set to a ip of a working iIs smtp relay for another application.  The working iIs smtp is working for 10 other server applications. Logs are saying "550.7.60 client does not have permission to send as this sender". I granted the vcenter ip relay permissions on the smtp server. I can't figure out why vcenter emails can't make it's way out the smtp server but the other applications can using the exact Office 365 email account. Thoughts?
Dear team, is there any method or batch script which can export PST file from MS outlook 2007/2010/2013/2016?

Many thanks in advance,
Dear Team, is there any safe method to move an EDB (of Exchange 2016 Server) from a domain (for ex: to the same environment but in different domain ( ? with note that the EDB already be imported data (PST files) from before
I had a spam problem about a month ago, which I fixed on my end.  I notice now that email I send to recipients at gmail are automatically being marked as spam.

My mail server is Unix - Communigate Pro running on an old PowerMac. Outbound mail goes to my SMTP server, which is a Dell SonicWall ES-3300    I changed the IP address after the spam got past the SonicWall, and put the new address into my DNS, which is hosted by

I looked at the header of a message I sent to my gmail account.  I see something wrong with the SPF record  

X-Mlf-Uniqueid: o201708020314430029673
Arc-Seal: i=1; a=rsa-sha256; t=1501643684; cv=none;; s=arc-20160816; b=fxKfyh5i6PzjoNNZkIMPSigH31cy4YQ3IwPn/XLlJekZPjdgLTVrCmwlzwGh2orLVN GAg7JYp8zmTIKmoj2fOo5/v5m9m+aMH16VJDa7PKxY2H5qYRt9OHehY+o6UqP95Il9lz 3/cqc1G6Fo+j3t0oCCa8H/JW4+03+o3X9nlX+ioY6gOoFGy7GtWzW4OJpxiJZUjxhtxp FgenvR03ekg/ZHQv7j3P/FIoDPhoQK/EzgofSx6a7qKwl0D4jY8YzBVvcQjfHYaJV96j porICVs9nghyv8bE7Oy34UxkqG3ZLJznTB4WqAmYzkC8Nw3duZRcC8G0B+ZXQXz1s7mi Jz0A==
X-Received: by with SMTP id p85mr27288566qki.281.1501643684625; Tue, 01 Aug 2017 20:14:44 -0700 (PDT)
Return-Path: <>
Arc-Authentication-Results: i=1;; spf=softfail ( domain of transitioning does not designate as permitted sender)
Dear Team, is it possible to import PST files which are more than 2 GB into Exchange server via Exchange Management Console? Many thanks in advance

In this article:, it said that "The PowerShell Command to import Outlook data file (.pst) to Exchange Server can’t import the file more than 2 GB."  

Can someone pls verify?
Dear Zealots, do you know any method to show the statistics in Google mail's usage. For details, we would like to have the report showing the frequency of email flows, like how many emails in weekdays and weekends, from 8 AM to 5 PM, from 5 PM to 10 PM, etc.

The same question in MS Exchange server. Can you please suggest? Many thanks in advance!

Update1: I found Gmailmeter, it could show me my statistics, but how can I see my end-users'?
Hi All,

When I enabled / redirect the Postmaster email from my Anti Spam appliance, I got to see the below emails coming in hundreds of them daily to my mailbox with the below error:

550 5.7.1 Bounce attack signature verification failed. (in reply to RCPT TO command)
550 Administrative prohibition - envelope blocked - (in reply to RCPT TO command)
550 #5.1.0 Rejected by bounce verification. (in reply to RCPT TO command)

How to resolve the problem above ?
My OS is win 10 pro 64 bit and I have office 365 and outlook owa for my emails , which is an MSN account the free version.
Whenever I see a sender of an email in the Junk folder, despite clickking on the "Not Junk" selection and it goes into the Inbox.  But after some time it still seems to land in the Junk folder.  
how do I make it safe emails coming to me to my Inbox without it going to my Junk email, or is this one of the misses that sometimes always takes place.
The error says that it failed the fraud detection test or something like that.
Thank u.
We aren’t perfect, just like everyone else. Check out the email errors our community caught and learn the top errors every email marketer should avoid.

Expert Comment

Comment Utility
Heh:-) Not too bad. I've seen worse!

Author Comment

by:Allie Watts
Comment Utility
Hey Arman! We know that opting in and out of certain emails is a problem for many members. We are working on giving members more options in their unsubscribe settings. Stay tuned for those updates!
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Help! I spent a few hours drafting a long heartfelt email to my children and when I hit save it save draft. Now I have gone to my saved draft folder and it is not there. Is there anyway to still retrieve it or am I sunk?
Dear Team, does anyone know how to configure 2 steps authentication in Exchange mail server? Is it possible? many thanks in advance.
Dear EE

Please can someone tell me what's the difference between the "From" and "X-Sender" field in message header?

We recently had a spoof and phising attempt on one of your users.

I have SPF in place and it works but it didnt stop this email because the X-Sender address is not that of my domain. My SMTP domain is

Please see image:

Where within the Gmail admin console can the external DNS mail exchange (MX) records be changed for an organization using Gmail for its email?
We have recently migrated from Exchange 2007 to Office/Exchange365. Since migration we have received a number of email rejections on one specific email indicating "your email program added invalid characters (bare line feed characters) into a message you sent".

The email itself comes from an HTML template and generated in Microsoft Dynamics AX. This is directed email to customers and is consistently accepted by some downstream providers (eg gmail, Hotmail) but not others (eg Yahoo, Comcast).

The HTML code that comprises the body text has been scrutinized and does not contain any bare LF's, nor has it changed since long before the migration.

Support from Microsoft, Yahoo and Comcast has been of little use (for the most part unwilling to engage other than throw out generalities to get you off the phone).

Key facts;
- email was working prior to (Exchange 2007 to Office365) migration
- other (text) email to affected customers is delivered without issue (ie limited to one HTML email)
- originating email has been checked for bare LF's

As this email was working previously I have the following questions;
- have you seen and resolved similar issues?
- As this was working previously I am wondering if Exchange 2007 stripped out bare LF's in order to fix (my understanding is that Office 365 was but stopped doing so).

Please do not suggest online articles found by Google searches unless you feel there is something very specific we can look at. We have searched …
I would like to make a parse of postfix mail log in an HTML/PHP page with a search bar and then creating a dynamic table with all these tags. when the table is done I should be able to click on the "Date" and another page should open with others info about that log *(2)

I will copy an example of a log

search: from: ...... to: ...... date: from: .... to: ....

Eg Table example: Date | time | from: Jack | to: John | status:


status detail

809318:Jul 11 14:13:50 amail-2014 postfix/smtpd[17127]: 78F5E83F28:[]
809320:Jul 11 14:13:50 amail-2014 postfix/cleanup[18135]: 78F5E83F28: message-id=<>
809324:Jul 11 14:13:50 amail-2014 postfix/qmgr[27711]: 78F5E83F28: from=<NO-REPLY@MOLEX.COM>, size=30390, nrcpt=1 (queue active)
809325:Jul 11 14:13:50 amail-2014 postfix/smtp[11782]: 78F5E83F28: to=<*****@SYLEX.SK>,[]:25, delay=0.73, delays=0.59/0/0.01/0.13, dsn=2.6.0, status=sent (250 2.6.0 <> [InternalId=50607599648815,] Queued mail for delivery)
809326:Jul 11 14:13:50 amail-2014 postfix/qmgr[27711]: 78F5E83F28: removed
809323:Jul 11 14:13:50 amail-2014 KLMS: not processed: …

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.