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 everybody,

i'am trying since a few days now to get my new exchange server to work.
the main problem is the incapacity to receive emails from outside, Inside the domain is no problem.
also sending emails internal and to external domains is no problem. OWA is working properly too.

impossible to configure Outlook with the exchange server, fot imap its reffusing the authentification and saying ActiveSync isn't active (but it is)

i get no error message when the emails didnt get received, also no error message while sending them from outside.

ports on firewall/router are open, DNS server is working properly.

if anyone has any idea to resolve this or if somebody needs remote access while iam avalaible, i can do that.

Best regards
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Dear Experts, we are using Exchange 2016 on-premise, the problem is when users send emails to incorrect addresses, the postmaster showed the error (in details) in MS Outlook but OWA.

The emails are synchronized from OWA to MS Outlook, but there is no content in postmater's email on OWA. Could you please suggest?
Dear Experts, can you please suggest us 2 problems:

1. How can we reset multiple Gmail accounts at the same time? (We are using Gsuite, and are Admin accounts)

2. How can we configure multiple MS Outlook accounts at the same time on Window OS?

Many thanks!
I've encouraged the user to contact Centurylink on this.  But maybe someone has another idea.

The user uses Centurylink Webmail.

When Composing or Replying, the names can be typed into the form.
But the Body cannot be typed into or Pasted into - at all.
Google Chrome shows a blank body that doesn't respond to a mouse click into it.
Internet Explorer shows "this page can't be opened" and mouse clicks also do nothing.

So, the user cannot send emails at all.

And, I can duplicate this on my own computer - which is entirely separate except for the email account login.
i am posing on behalf of a friend whose gmail was hacked and now the hacker is posing as my friend and trying to carry on his business activities.   How does one stop the hacker, and how does one take the remedy with google.  Are there any steps to follow.  Thank u. Regardss
Is there a way for pop3 or imap account to sync calendar with gmail as alternative?
Or to import the pop3 or imap calendar to gmail account?
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.
We have a legacy software that does not support TLS so we relay the emails via an IIS relay that authenticates and send out via Office 365.

Emails to certain recipients are bouncing with the NDR 550 5.6.11 SMTPSEND.BareLinefeedsAreIllegal

This has just started recently about 2 months ago .

This Microsoft links explains why -

 What's a bare line feed in email messages?

Usually each line of characters in an email message ends with a carriage return followed by a line feed (CR LF). A bare line feed is a line feed (LF) character that is not immediately preceded by a carriage return (CR) character. In other words, instead of a line ending with CR LF, it ends with only LF.
This worked fine before, why did it stop working recently?

Until recently, Office 365 automatically removed bare line feed characters from mail to help it get delivered to recipients using older email servers that don’t support chunking and the BDAT command. The support for BDAT is required by the email industry standards referenced in RFC 1830. In an effort to better support security standards, like DomainKeys Identified Mail (DKIM), Office 365 no longer removes bare line feeds from messages. As a result, messages sent to users with older mail servers may be more likely to be rejected.

Their suggestion is to make changes on the recipients server which is not possible so what can I do on our end to fix this?
We are having an issue where users are not receiving delayed delivery status emails but they are receiving failed delivery notifications.  The option is set to notify sender when message is delayed by one hour but no one ever receives it.  Any ideas?
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 :-)
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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?
We have a hybrid Exchange environment, Exchange 2016.

I need to be able to relay messages to external recipients, but I do not want an open relay.

I have a receive connector setup as
port 25
TLS, Basic Auth, Exchange auth
permissions to Exchange servers and anonymous user (for testing)
Allow mail from all servers (0-255) (for testing)

I have a send connection setup as
Proxy through client server
route mail to MX record (or smarthost for filtering)
Address space SMTP *

I am still receiving the error
550 5.7.54 SMTP; Unable to relay recipient in non-accepted domain

Please help me find what I am missing and get the relay working.
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: …
I got a mail from was it real or not please tell me
I have one client that cannot email me.. They receive a bounced back message saying;

550 Verification Failed
No such user here
Sender verification failed

I can however email them. But they cannot reply.

None of their emails from their domain will come through, however I have been guaranteed from my ISP (crazy domains) that there are no blocks on my end. However i do know of another company who are with crazy domains are experiencing the same problem with the server  

As I run my ow  business, my only option is to change hosting companies in the hope that works.

Would love an easier fix
Dear All,

I have a question. When my clients send their transactional emails using my provided SMTPS, I process the MTA logs to generate bounces and track emails. I need some guidance here, how would I put my web application in the middle of MTA and the client so if any client sends any transactional email using the provided smtp, it pushes the email to my application first and then my application pushes it to the mta after filtering it.

Thank You
I changed the password on a account and now it is failing.  It keeps asking me to put in the log in and password and when it tests an email, it fails to connect to server.  I have tried deleting the email and reinstalling it.  It won't reinstall it.  I have tried using the old password.  Nothing is working.
I have Dropcam (now Nest) forward mail to three different email addresses.  Often, one relay entity is very slow (just now, 111 minutes).  This is usually ""  Why and what should I do about it?
I want my mail address back
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User get the error message attached

The laptop has been formatted but the issue still exists. It happens only to this user
I have postfix installed on a fedora linux server.  It works for the most part.  I can receive mail and reply via webmail.   It does not work for mail clients.  It will receive mail okay but you cannot sent outgoing via my mail server.  
Plus gmail will not accept my emails because I do not have encryption set up.    Post fix was installed by another admin and I do not want to lose the functionality I have but I need to get up to speed with encryption and being able to send emails from an email client.  
Help please.
I have a custom developed (Mail Service Process) that gathers notification information from various customers, and then builds a notification email and then sends that email through a smtp server (mail chimp).

Some times my (MPS) server or process fails and the emails stop being sent out.  I need to know when we stop sending out emails.  Unfortunately, the server is still running, and the Service is still running, it's just not sending the emails.

I'm thinking I could send (on a schedule, like every 5 or 15 minutes) a genetic "status" email to somewhere external that is watching, and will notify me that the status emails are not showing up, rather than me finding out when a customer realizes they are not getting emails.

Sort of like a deadman switch for outgoing email.

Does anyone know of such a service?  I have seen services that do full send/recv email account verification, but that is not the same.
Hello Expert,
                       In our CRM software application, we track if an email is opened by sending  an image. But for gmail and yahoo, from recent past, we are not able to track the open status and update in our database.

we use below link to check the mail status:
<img  style=\"background-image:url('"+ DomainName + "MailStatus.aspx?type=open&MailKey=" + mailKey + "&DB=" + Session["PMSFolder"] +"');\" src=\"\">"

This code works in some mail servers but in Gmail and Yahoo mail servers.

URL we send:   src=” Images/e-con-logo.png "

When we check after opening the image in the inspect element. it contains exact src path in some mail servers but in gmail some additional content is added  in src as shown below below:

src=" Images/e-con-logo.png ">

Please help us address this to track email users.

I have a task to urgently install POP3 service for and existing exim installation on Debian 8.
Which POP3 server is the best? Please link configuration guide if possible.
We are experiencing intermittent and significant delays in receiving emails from various 3rd parties from various domains (no rhyme or reason as to which sending domains).  The issue is intermittent.  Sometime no problem, sometimes up to a 33 hour delay receiving an email.  The issue is being experienced from private domains, gmail,, etc.  We checked the route trace on several emails and the delays appear to consistently be in the step where the mail is received by our server.  See attached screen shot for a google app report of the route trace.  We have not been able to pinpoint any external reasons, the mail domain is not on a blacklist and we are able to reach the email server from offsite locations (since the issue is intermittent, but we have not identified any external reasons for it).  Internally once the mail hits the server it routes immediately, so we know that once the mail hits our server it is on the users desktop in a matter of seconds.  Any assistance or direction on this issue is appreciated.

Google Apps route trace

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.