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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My emails sent from my gmail account are not delivered to accounts

I send an email to ******* (my accoint too)

And it is never received. An my gmail account gets no undelivered message.

All other gmail accounts I have tried send to and are received fine.

Prodigy aupport says it is a gmail problem.

I am at a loss.. I ahve neve aabused my account in any way.

Is there a way to trace what happens one the emails are sent? To see where they are being stoppned from delivery?

Learn Ruby Fundamentals
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Learn Ruby Fundamentals

This course will introduce you to Ruby, as well as teach you about classes, methods, variables, data structures, loops, enumerable methods, and finishing touches.

We currently use EWS to move emails from the inbox of one mailbox to the inbox on another mailbox based on specified criteria. The code is as follows:

private void MoveEmailToAttacherMailbox(string id, string attacherMailbox)
      DocStore.Logger.Info(string.Format("{0} id: {1} To attacherMailbox: {2}", (object) nameof (MoveEmailToAttacherMailbox), (object) id, (object) attacherMailbox));
        Item.Bind(this.exchangeService, (ItemId) id).Move(new FolderId(WellKnownFolderName.Inbox, (Mailbox) attacherMailbox));
      catch (Exception ex)
        Exception exception = ex;
        DocStore.Logger.WarnException(nameof (MoveEmailToAttacherMailbox), exception);

Unfortunately since 29th November we have been getting an error: "MoveEmailToAttacherMailbox Microsoft.Exchange.WebServices.Data.ServiceResponseException: The move or copy operation failed."

No permissions have changed and the mailbox we are moving from has full delegate permissions to the mailbox we are moving to. Any assistance will be greatly appreciated.
In a Nation Builder nation, I have a 700-member e-mail recipient list. The majority of these recipients were imported when my nation was set up a couple of months ago. Email to these recipients is solicited because they all pay a monthly/annual fee for membership.

I've sent about a dozen email blast in this time without problem, and I get stats on how many people opened links inside the emails, how many bounces, how many are ad addresses. However a couple of weeks ago, I sent one out and it first reported everything to be OK, with zero bounced, but after about 4 days, the bounced shot up to 117. This was highly irregular because the highest number of bounces before this was about 8. I had a look at the 117 and they are all Yahoo, AOL or Sky addresses, and since AOL and Sky go through Yahoo, we can assume that this is specifically a Yahoo problem. Here's the message that appears in Nation Builder next to each bounce...

4.0.0 Email was deferred due to the following reason(s): [IPs were throttled by recipient server]

I've done two more blasts since this, and the same thing happens. I've checked with a few owners of these email addresses and can confirm that the emails are not being received.

Is there anything I can do to help this situation, either on Nation Builder, on Google G-Suite, or on Yahoo? I've contacted Nation Builder support, but all they suggested was that I send a handful of emails at a time in order to rewarm Yahoo. But this could take a long time, …
well  how can I decode the emails  so i can get plain text?

import poplib;

import io;

import string;

import encodings;


 server = poplib.POP3_SSL("",poplib.POP3_SSL_PORT);




response = server.user('');

response1 =  server.pass_('XXXXXXXX');



# download the first message in the list

messages = server.list();



Open in new window

help appreciated
Hi - I have an IMAP email account that was setup correctly, and all email was downloaded into Outlook as it normally does. I'm having a strange issue where I don't see any email from today or yesterday, the latest date that shows on top (sorted by newest) is Monday. The strange part about it is, that if I do a search in Outlook for something, it does show email from yesterday, but only when I search. I've checked the IMAP folder settings to make sure that "hide messages" is not set, and it isnt. I've also checked to make sure that the "TODAY" email group is not collapsed and out of view. I'm not sure where to go with this. Any ideas would be greatly appreciated!
On a Canon IR-ADV 5235, when Scanning to Email, if the files are beyond a specific file size it will split the emails in two, with the attachments.
I would like to specific the maximum scan/file size that it can send, so that it doesn't split the file in 2.
Dear Experts, we have several Exchange 2016 servers (VMs) in Vsphere 6.5 environment, but one SAN storage is running out of space.

How can I check whether if we can delete some space in Exchange Database? Due to company policy, we have to keep disabled mailuser for a year; but in urgent they can be deleted.

But I'm not sure to check the space which was taken by those disabled accounts. Can  you please help? many thanks!
My brother-in-law has forwarded an email conversation to me that was initiated by a request for the payment of an invoice that did not exist. The spam email appears to have come from his email address and was sent to people in his address book. I was wondering if someone could help me to recognise whether the spam email is a spoof or whether someone or something has managed to hack into the email account. I have no real experience of reading email headers so please be gentle.
Thank you in advance.
I have a client using IMAP in Outlook. Yesterday she wasn't receiving any emails. I looked at the account settings, and they were all correct. I tested the connection, and the test message went through just fine. Then I closed the windows. After a second or two, her emails started coming in. This morning, she again was receiving no emails. I checked the settings again and again tested the connection, then closed the window. Again, after a moment or two she started receiving emails. She never has a problems receiving emails on her phone (also IMAP). It's like every day I have to remind Outlook it can find the server by testing the connection. This is very inconvenient. What can I do?
I'm configuring postifx mail server in centos 7. i have facing problem related rate limit outgoing mails. my requirement is 3 mail every 1m. so what type of configuration in and i hope you will help me.

Thank you
OWASP: Forgery and Phishing
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OWASP: Forgery and Phishing

Learn the techniques to avoid forgery and phishing attacks and the types of attacks an application or network may face.

I have a website on an internal domain. It's hosted on IIS and uses some javascript scripts and SKEL for for content generation, resizing, it works well as a responsive web page.
There is a form to send email, it is centered around using an external email provider. I have set it up so that it puts the requested data, (type of info requested, name, email, etc) and puts that where it belongs in the users own default email client. (generally Outlook). We have our own SMTP server.
My question is what is the simplest approach to get email sent using the form? The server is Windows server 2016, IIS. I have looked up stuff and see PHP, ASP it's kind of crazy how complicated it gets. Maybe I have not found the right tutorial.

I was trying to send emails through powershell on a computer PC01. and received error message blow
"InvalidOperation: (System.Net.Mail.SmtpClient:SmtpClient) [Send-MailMessage], SmtpException"

I also tried to run the same script on another computer PC02 in the same subnet. it worked.

Both PCs can telnet to the smtp server on 25 successfully.

I have also tried to use ISP smtp to send email which was the same result PC01 didn't work with the same error. PC02 worked.
I checked the even log, no outstanding errors or warnings found.
I have also tried to turned off firewall and antivirus program without luck (which shouldn't be the issue as I can telnet to port 25 on the smtp server)
We have a single user who is unable to send email outside of our organization due to multiple kickbacks with following NDR
Remote Server returned '550 5.7.501 Service unavailable. Banned Sender
I have verified by searching the various online spam lists ( spamhaus, etc) that our domain is not on any list and the issue does not seem to be effecting any of our other users. This user had his account hacked last week and we discovered it was used to send a large amount of spam before we reset his account.
I am unable to find a solution to resolve kickbacks for a single email address.
We have been struggling with setting up our website on a GoDaddy Virtual Private Server. Please Help!

We have a .net program that connects to First Data to process credit cards. It running on a Windows 2012R2 + Plesk Virtual Private Server hosted at GoDaddy.We need to send confirmation emails from the server after a transaction is processed. I am attempting to send an SMTP email on a GoDaddy Plesk VPS and am having difficulty with the syntax.  Here are examples of what has been tried with the corresponding error messages.

email that I'm sending is now going to my customers spam boxes.  kinda happened out of the blue.  its not bulk emails.  its individual emails the i type with info for my clients.  i do copy/paste some info that goes into each email as well.

been working fine for years...its just all of the sudden everyone is saying that email is going to their junk boxes.  

its my own private domain email, i use gmail as the client for checking and sending it.

i havent changed anything on my end.  what do I need to look for to see what is going on?  TIA
as many others I have also problem #550 4.4.7 QUEUE.Expired; message expired ##
Exchange 2010 works fine for years, suddenly is refuse to send mails to some e-mail addresses.

I checked, MXtoolbox
reversed dns (PTR) is set
in exchange send connector FQDN is filled in and is the same as the PTR

please advice,

Many thanks Victor

I have a strange Problem. I am not getting some emails from some recipient, the TXT emails are delivered without any problem but with PDF attached emails are not passing through.
Even Message tracking it not showing but in SMTP receive logs its showing delivered

8847,>,250 XProxyFrom accepted,
8847,<,MAIL FROM:<> SIZE=0 AUTH=<>,
8847,*,SMTPSubmit SMTPSubmitForMLS SMTPAcceptAnyRecipient SMTPAcceptAuthenticationFlag SMTPAcceptAnySender SMTPAcceptAuthoritativeDomainSender BypassMessageSizeLimit SMTPSendEXCH50 SMTPAcceptEXCH50 AcceptRoutingHeaders AcceptForestHeaders AcceptOrganizationHeaders SendRoutingHeaders SendForestHeaders SendOrganizationHeaders SendAs SMTPSendXShadow SMTPAcceptXShadow SMTPAcceptXProxyFrom SMTPAcceptXSessionParams SMTPAcceptXMessageContextADRecipientCache SMTPAcceptXMessageContextExtendedProperties SMTPAcceptXMessageContextFastIndex SMTPAcceptXAttr SMTPAcceptXSysProbe,Set Session Permissions
2018-03-04T13:01:48.037Z,GSEXCHMC1\Default GSEXCHMC1,08D57BA60716263A,263,[2002:c864:6406::c864:6406]:2525,[2002:c864:6406::c864:6406]:8847,*,08D57BA60716263A;2018-03-04T12:54:14.609Z;12,receiving message
<,RCPT …

So we are working to configure Mandatory TLS security between 2 email domains. We have control of one, which we need to get this configured for.

They are currently using Office365 which routes through Mimecast for email filtering etc.

So my understanding of it is that we configure this on Mimecast only for incoming and outgoing mailflow, however, I am struggling to see how it works correctly, when it needs an SSL certificate from Office365 in order to work correctly?

Do we also need to configure inbound and outbound connectors for this TLS requirement on Office365?


I am  writing send-mail program in android. it is working OK.
but in case, if we have problem in connecting smtp server or it might bounce back for some other reason..
(My question here  is )
if the sent mail is bounced back for some reason, how to judge inside the android code for the smtp errors and retry sending it later...
several times or for specified tries till it reaches the receiver..
Can any  one  share the code for  queuing emails.. and handling smttp errors. etc.
Thanks in advance
Build an E-Commerce Site with Angular 5
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Build an E-Commerce Site with Angular 5

Learn how to build an E-Commerce site with Angular 5, a JavaScript framework used by developers to build web, desktop, and mobile applications.

I have a c# program I am working in that I did not originally create.  I need to add an email element that will create a PDF with graphics (like the attached) authenticate with an email server (like gmail, microsoft or similar) and send that email to a specified address.

I am not sure where to begin, especially on creating the data based graphic.

My ex boyfriend hacked me and deleted/or changed my Gmail  account how can I get it back?
Is there an easy was to set up email (other than standard received notice) to determine if an email sent has been received. We keep having issues with our emails not received.
Our client (a sort of golf travel company) in the UK regularly sends out email worldwide to their clients. They are now receiving bounce-backs in German, making it difficult for my client to resolve them. The user sending the orginal emails is

I have contacted  the ISP (Fasthosts in the UK) and they understandably say "This would only happen if the e-mail you are sending to is hosted on a German server as the bounce back is sent from the server rejecting the e-mail." however, our client receives these from all over the world always with the same formatting, so they seem to be coming from the same generating program, if not the same server?

I attach some of the bounce messages (they're in Outlook Item file format).

I suppose the other issue is what are these, or what's causing, the bounce-backs in the first place?

I am sure those of you who "enjoy" trawling through email bounce headers will find this a fun challenge :-)
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?
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.