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.

Share tech news, updates, or what's on your mind.

Sign up to Post

My email issues are continuing, but only with domains hosted by Yahoo. My Spf record is correct and I have fixed my ptr record today as well (Finally in place around noon). Here are my DNS Records and a screen shot of the issue. This issue is only occurring with email addresses or domains hosted by Yahoo. Everything else works as expected.
HTML5 and CSS3 Fundamentals
LVL 19
HTML5 and CSS3 Fundamentals

Build a website from the ground up by first learning the fundamentals of HTML5 and CSS3, the two popular programming languages used to present content online. HTML deals with fonts, colors, graphics, and hyperlinks, while CSS describes how HTML elements are to be displayed.

A client of our's email isn't working via outlook. I thought perhaps the pst was bad, but it is failing on all computers with outlook. I tested on their system to the web version and it signed in fine. I went back and deleted the mail account on their computer and set it up as active sync and it works fine from outlook. However, if I try to add their email as an IMAP as it is created on the mail server, it fails.

I adjusted the IP from 143 to also try 993. Also attempted with the firewall disabled. It was working fine for a while up to today. The error is uploaded.
I would like a script that I can modify to be able to the following:

Use Office365 smtp
Port 587
to accept username and password
have a pdf attachment to it called 1.pdf
Send to a distribution list from. EmailList.txt
msg-header.PNGmail delay

one of the user complain receive one email from one of the recipient facing mail delay issue ,i using mx tools box and found that is one hours delay from recipeint server to our server  ,please advice what should i do ?
I am trying to send rather important emails to a person in the USA that has a Cox network address. They are all bouncing back to me with the message: This is the mail system at host

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your own text from the attached returned message.

                   The mail system

<the guy I am trying to email address>: host[an ip address] said: an ip address
    <my email address> server temporarily unavailable. Refer to Error Codes
    section at
    for more information. AUP#CXMXRT (in reply to MAIL FROM command)

Is this a problem with MY email provider or Cox? How do I solve this the easiest way possible?
Using my gmail account to send an email, is it possible for the recipient to know which country I sent the email from if I was travelling?  The same question applies to any any provider other than gmail.
I have an email account. It has the form:
In order to login to the email I have to browse to the website and, in order to log in to my email I have to enter the following details:
password: password1 [This was a password of my choosing]
Despite the fact that I provide authentication details on the website, once I am authenticated, I am diverted to a Gmail account with the company logo in the top right corner.

I would now like to transfer all of the emails from this (Gmail) account to another new, personal Gmail account. In order to do that I have been into the settings of my new Gmail account and used the "Import mail and contacts" process. The authentication details that I then provided in order to fetch the mail from the pop server were:
password: password2 [This is a random-looking password provided to me by the company]
pop server:

I successfully managed to set the "Import mail and contacts" process going. Unfortunately, it only transferred two thirds of the emails. Gmail did not provide any error message. It took me a while to work out that the company Gmail has a 30GB limit whereas the new personal Gmail has a 15GB limit and when it reached 16.5GB, the import stopped.

I purchased the 100GB package. Once this was in place, the import did not start up again. When i tried to start it off again, I just ended …

I'm looking for a SMTP test tool which:

- Can use TLS connection
- port 587.
- can add username /pw

Any idea where I get a that tool?
Dear Experts

I am hoping someone can assist me with the following issue. I have SPF and DKIM configured on my domain, which appear to be setup correctly but when I examine the message header of an email I sent I see the following entry "None ( does not designate permitted sender hosts)"

Just to add I am using Exclaimer for signature management.

Please can someone examine the header below and advised if I configured something incorrectly.

Received: by 2002:a4f:c15:0:0:0:0:0 with SMTP id 21csp930979ivm;
        Wed, 21 Aug 2019 06:30:56 -0700 (PDT)
X-Google-Smtp-Source: APXvYqyk6Zvuz4Zzp1WUwoJQlz3EsF/mENO5B7uNOXkWXKiQUJ9CmIl25//eS3gDvDa/NqaFIZJg
X-Received: by 2002:a17:906:158c:: with SMTP id k12mr31626198ejd.83.1566394255976;
        Wed, 21 Aug 2019 06:30:55 -0700 (PDT)
ARC-Seal: i=2; a=rsa-sha256; t=1566394255; cv=pass;; s=arc-20160816;
ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed;; s=arc-20160816;
Hi Experts,

I have a some problem to understand some things on Exchange 2016.

First of all, I want to explain how works my exchange :

  1. DAG - 3 members
  2. 1 Edge on the DMZ :
  3. 1 Fortigate to do the link between the Public IP and the EDGE on the DMZ : Client -> Public IP  -> EDGE Server
  4. Here the smtp :
  5. I have an external Client who send mail through our Exchange :

Then, I have a receive connector on the Edge :
AuthMechanism                             : Tls, ExchangeServer
Banner                                    :
BinaryMimeEnabled                         : True
Bindings                                  : {}
ChunkingEnabled                           : True
DefaultDomain                             :
DeliveryStatusNotificationEnabled         : True
EightBitMimeEnabled                       : True
SmtpUtf8Enabled                           : True
BareLinefeedRejectionEnabled              : False
DomainSecureEnabled                       : False
EnhancedStatusCodesEnabled                : True
LongAddressesEnabled                      : False
OrarEnabled                               : False
SuppressXAnonymousTls                     : False
ProxyEnabled                              : False
AdvertiseClientSettings                   : False
Fqdn                                      : SRV-DAG-EDGE.contoso.local

Open in new window

Introduction to Web Design
LVL 19
Introduction to Web Design

Develop a strong foundation and understanding of web design by learning HTML, CSS, and additional tools to help you develop your own website.

How can I send a text from my computer to a mobile phone number if I do not know the name of the carrier?
I have an existing Outlook 2013 setup with one POP3 email configuration. I purchased a new POP3 email account that I wanted to add to the existing Outlook Profile, set as default, and remove the  original. I believe I made a mistake deleting the original POP 3 account  from my registra before removing it cleanly from Outlook.  So, when I went to open the account settings within Outlook, it won't open. I am unable to access the account to delete it from the OUtlook Profile. Luckily I was able to switch the default to the new POP 3 account so Outlook does open, yet I believe I will have problems with  the  calendar, tasks, etc. I already know I am  unable to reply from the new account.

How can I get rid of the original email account, and have all the Outlook functions (Calendar, Tasks, Contacts, etc.  associate to the new user?
Hi Experts,
I am looking for a program that will keep checking at a particular folder every 20 minutes, if there were no new files created then will send an email.
This should be running all the time except for night hours (10.15 PM to 6.00 AM).
We have an Online Exchange (O365). We have multiple affected users with the same issue and is persistent across all versions of Outlook.

The users have full delegate access to a Shared Mailbox. They are able to view and access the mailbox just fine in Outlook, but the Shared Mailboxes also have In-Place Archiving enabled. These show up in the delegates users' Outlook as Online Archive - . But when attempting to access the Online Archive via Outlook, they are getting the error message:

"The set of folders cannot be opened. The file C:\Users\user\AppData\Local\Microsoft\Outlook\ - Example.ost is in use and cannot be accessed. Close any application that is using this file, and then try again. You might need to restart the computer.

We have confirmed that the users are able to connect to the Shared Mailbox via OWA and access the archives there, this issue is solely isolated to Outlook.

We have tried purging the AutoDiscover keys in the registry, creating a new email profile in Outlook, and deleting the OST files and Outlook cache to no avail.
We have an org with both 2010 and 2016 exchange all on premises.  The 2016 servers are in Europe and we originally had them using "" as UPN and primary SMTP.

The business has asked us to change everyone to a "XXX@Company.COM"  UPN and Primary SMTP.

We have users in the .eu that have been using in-place archives with no issue.  Once their UPN and Primary SMTP has changed they now cannot access the in-place archive.

They (the .eu users) are on a separate network (acquired company in process of getting onto our network) and use Outlook Anywhere.

There is a mix of Outlook Office Pro 2010 and 2016.  
We have recreated profiles and still not working,

The 2010 Outlook clients can see the archive but it says it cannot connect if clicked on.
The 2016 Outlook clients - the archive never shows up.

All of then can get to the archive via OWA with no issues, and I can add a profile from on our network with no issues and see the archive no problem.

Is this an autodiscover issue ??  What am I missing?

Thanks in advance!
I have users with a primary email domain as  They also have aliases of and  What I need to happen is that I want the user to be able to change the "From:" email from their primary at any time incase they have to show as a different email address for legal purposes.  

I attempted this with outlook and entered in one of my aliases on the from line but the recipient still shows as my primary and not the address in the "From:" I manually entered.  Any help would be greatly appreciated
Can someone who understands DMARC explain to me exactly what is happening in this DMARC?

spf=neutral ( is neither permitted nor denied by best guess record for domain of;
dmarc=fail (p=NONE sp=NONE dis=NONE)
Return-Path: <>
Received: from ( [])

is not authorized/allowed to or is not authorized/allowed to
We are setting up SPF, DKIM, and DMARC for our domains but just wanted to get some clarification on the best options to set for each scan result:
none, neutral, softfail, hardfail, permerror, temperror

So basically wanting to know which is the best option?
From reading it seems that HardFail would be the way to go but just wanted some insight for these settings and what is the best practice for them to set them up?
Amazon Web Services
LVL 19
Amazon Web Services

Are you thinking about creating an Amazon Web Services account for your business? Not sure where to start? In this course you’ll get an overview of the history of AWS and take a tour of their user interface.

Hello, I have a specific setup where an application can only send mail through port 25 but it needs to run at customer premises where the internet access filters outgoing port 25 which is not too uncommon. To solve this I have utilized a very simple mail proxy (URL below) that runs as a local SMTP server on port 25 and then forwards it to an external SMTP server using alternate ports.

This proxy setup works fine for mail only, but now I have the added user requirement that the mail also should handle attachments and the proxy below does not seem to do that.

Are there any very simple mailproxys available like the one below that also can handle mail with attachments? Thanks in advance
Finder and deleting old Mac Thunderbird emails

I have deleted a handful of old email accounts in Thunderbird. But, I forgot to always check the checkbox to remove the associated emails.

Now, I am asked to compress the emails, which are ~275 GB.

Is there a way to find these folders and delete them manually?

I have to design a little email tool for sending semi-automated mails to customers on behalf of employees who don't have enough time to do by theirselves. Information about mail targets (customers) are taken from a database, a mail template is used and filled with the appropriate information. At least that mail is sent out to the customer and a bcc is sent to an internal 'archive' mail address. My tool's basically working and sending mails out. But here are the requirements (and my related problems):

1. If target mail address is not correct or something goes wrong within the mail transport, the error mail must not go back to the employee (which name and address is used in the from tag). Error mails should go to a different 'pool' address, where an operator may compare and correct against the database.

2. If customer replies to the mail, that reply should go to the employee rather than to a 'pool' address or operator.

3. The mail should optically appear to the customer as if it has been sent from the employee.

I need an example on how to create the mail headers to accomplish exactly that behaviour (or one close to that). I tried some combinations and I read the RFCs, but I couldn't get the required results so far.

Any help is greatly appreciated.

Our organization maintains email addresses through Google G Suite.
  • In the past we offered private email to people associated with our organization (like:
  • We now want to restrict organization email to business accounts.
  • I would like to have personal accounts disabled, but with a forward that will send on personal email to a other providers for a period of time.

Anyone know how to do this?
My client uses gsuite and a CRM program to send mail. I have configured the gsuite properly for SPF, DKIM and DMARC. But DMARC is showing me that the client is also using SENDGRID.NET to send mail. After investigation, we found that the CRM is created by a third party, and ALL the mail goes through their SENDGRID account, leaving no way to to individually configure it.

I created an SPF record for this, but I would like to create a DKIM record. There is a DKIM-Signature in the header of the email from sendgrid. Is there a proper way to create a TXT record to store this information? Would I need to add this to the current TXT record used by gsuite or would I make a new one?

Thank you.
The user has a brand-new email account, and wants to control what senders they receive email from.
They have an Exchange account with Intermedia, a large hosting company.

I recall there being a company that had a system which receives and holds the email, notifies the user, and waits for the user to approve senders.

Can anyone tell me what companies offer this service?

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.