Outlook not connecting POP3/IMAP clients SSL/TLS

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Hi Faris,

May I know how did you configure Outlook to connect via POP3 or IMAP? Please provide the specific settings you used here so that we can check whether there is any misconfiguration.

What error did you get when it failed to connect to the mail server?

Please check whether you have started the Microsoft Exchange POP3 service and the Microsoft Exchange POP3 Backend service. By default, these services are not started.

Regards,
Steve Fan

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Proposed as answer by Steve Fan Wednesday, February 13, 2019 9:33 AM

Tuesday, February 12, 2019 6:15 AM

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Hi Faris,

Any update here? Please don't hesitate to post back if you need further assistance here.

Regards,
Steve Fan

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Wednesday, February 13, 2019 9:34 AM

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The above are the error am getting while attempting connect by using SSL/TLS with port 587 SMTP and POP3 995, the same happens for IMAP as well. If make 'None' the outlook getting connected without any issue.

The outlook POP3&IMAP service are running, i have already outlook POP3/IMPA which are are connected exchange server with NONE option.
Recently i have applied SSL on my exchange and applied to IIS,POP/IMAP/SMTP.

When i search, i noticed that some article states the SCP/SRV records to be created for autodiscover, as of now i dont have such records in my local DNS and public. I have only autodiscover A records which poiting to email server.

I would expect your best advise to get it done. !!

Thank you in advance for your valuable time.

Faris

Wednesday, February 13, 2019 8:25 PM

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Hi Faris,

Thank you for your reply.

According to the screenshots you provided, I understand that Outlook clients could access with Exchange server and it failed in sending test messages.

After enabling and configuring POP3/IMAP4 on the Exchange server, you need to configure the authenticated SMTP settings for POP3/IMAP4 clients so they can send email messages. The brief steps are like below:

1. Configure the FQDN on the "Client Frontend <Server name>" Receive connector.
2. Specify the certificate that's used to encrypt authenticated SMTP client connections.
3. Configure Outlook on the web (formerly known as Outlook Web App) to display the SMTP settings for authenticated SMTP clients at Settings > Options > Mail > Accounts > POP and IMAP.

More details please review the link below:

Configure authenticated SMTP settings for POP3 and IMAP4 clients in Exchange Server
https://docs.microsoft.com/en-us/exchange/clients/pop3-and-imap4/configure-authenticated-smtp?view=exchserver-2019#step-1-configure-the-fqdn-on-the-client-frontend-server-name-receive-connector

Service connection point (SCP) AD object is created when an Exchange Client Access Server installed. The SCP object is used by domain joined clients to locate the Autodiscover service. Generally, the Exchange external Autodiscover DNS entity is configured as a regular A record. In your environment, it doesn’t need additional SRV record to instead.

Regards,

Manu Meng

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Edited by Manu Meng Friday, February 15, 2019 8:37 AM

Friday, February 15, 2019 8:32 AM

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Hi,

I have gone through your article, now am able to connect Outlook POP3/IMAP TLS with in Local network, but SMTP SSL not getting same error.
in the same time, am unable to get connected on both SSL/TLS from outside network. where all the ports are SSL/TLS are open in my internal firewall.

In OWA, i can see the POP/IMAP server setting details.

POP3 Settings

Server name: mail.mydomain.com
Port: 995
Encryption method: SSL

IMAP Settings

Server name: mail.mydomain.com
Port: 993
Encryption method: SSL

SMTP Settings

Server name: mail.mydomain.com
Port: 587
Encryption method: TLS

Could you please advise where i mistaken.

Faris

Sunday, February 17, 2019 5:50 PM

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Hi Faris,

>>I have gone through your article, now am able to connect Outlook POP3/IMAP TLS with in Local network, but SMTP SSL not getting same error.

Do you mean you can successfully connect to Exchange via POP3/IMAP TLS now? What does "but SMTP SSL not getting same error" actually refer to?

>>in the same time, am unable to get connected on both SSL/TLS from outside network. where all the ports are SSL/TLS are open in my internal firewall.

Please use the Exchange Server > POP Email test or IMAP Email test in the Microsoft Remote Connectivity Analyzer to test POP3/IMAP client connectivity to the Exchange server. Please post back with the testing result.

Regards,
Steve Fan

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Tuesday, February 19, 2019 6:53 AM

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HI,

I mean being able to connect Outlook POP3/IMAP by using TLS in Local network but not connecting SSL in POP3/IMPA.

and am unable to connect POP3/IMAP over the internet on both SSL/TLS.

Below is the result of the connectivity test.

Connectivity Test Successful with Warnings

Test Details

Testing POP for userDOMAIN \test1 on host mail.domain.com :995<g class="gr_ gr_442 gr-alert gr_gramm gr_inline_cards gr_disable_anim_appear Style replaceWithoutSep" data-gr-id="442" id="442">:SSL</g>.

POP was tested successfully.

	Additional Details
	Elapsed Time: 3480 ms. mail.domain.com

Test Steps

Attempting to resolve the host name mail.domain.com in DNS.

The host name resolved successfully.

Additional Details

Testing TCP port 995 on host mail.domain.com to ensure it's listening and open.

The port was opened successfully.

Additional Details

Testing the SSL certificate to make sure it's valid.

The certificate passed all validation requirements.

	Additional Details
	Elapsed Time: 636 ms.

Test Steps

The Microsoft Connectivity Analyzer is attempting to obtain the SSL certificate from remote server mail.domain.com on port 995.

The Microsoft Connectivity Analyzer successfully obtained the remote SSL certificate.

Additional Details

Validating the certificate name.

The certificate name was validated successfully.

Additional Details

Certificate trust is being validated.

The certificate is trusted and all certificates are present in the chain.

Test Steps

The Microsoft Connectivity Analyzer is attempting to build certificate chains for certificate CN=mail.domain.com, OU=Domain Control Validated.

One or more certificate chains were constructed successfully.

Additional Details

Analyzing the certificate chains for compatibility problems with versions of Windows.

Potential compatibility problems were identified with some versions of Windows.

	Additional Details
	The Microsoft Connectivity Analyzer can only validate the certificate chain using the Root Certificate Update functionality from Windows Update. Your certificate may not be trusted on Windows if the "Update Root Certificates" feature isn't enabled. Elapsed Time: 0 ms.

Testing the certificate date to confirm the certificate is valid.

Date validation passed. The certificate hasn't expired.

Additional Details

The POP service is being tested.

The POP service was tested successfully.

Additional Details

Successfully tested the POP3 service
Secured: CN= <g class="gr_ gr_488 gr-alert gr_gramm gr_inline_cards gr_run_anim Style multiReplace" data-gr-id="488" id="488">mail.domain.com </g><g class="gr_ gr_488 gr-alert gr_gramm gr_inline_cards gr_disable_anim_appear Style multiReplace" data-gr-id="488" id="488">,</g> OU=Domain Control Validated
S: +OK The Microsoft Exchange POP3 service is ready.
C: CAPA
S: +OK
TOP
UIDL
SASL PLAIN
USER
.
C: USER test1
S: +OK
C: PASS <password>
S: +OK User successfully logged on.
C: STAT
S: +OK 22 239726
C: QUIT
S: +OK Microsoft Exchange Server 2016 POP3 server signing off.

Elapsed Time: 2178 ms.

Faris

Edited by Farispv Tuesday, February 19, 2019 6:27 PM

Tuesday, February 19, 2019 6:26 PM

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IMAP Test Result.

mail.domain.com

Connectivity Test Successful

Test Details

Testing POP for user DOMAIN\test1 on host mail.domain.com:110:TLS.

POP was tested successfully.

	Additional Details
	Elapsed Time: 2784 ms.

Test Steps

Attempting to resolve the host name mail.domain.com in DNS.

The host name resolved successfully.

	Additional Details
	IP addresses returned: 1.1.1.1 Elapsed Time: 10 ms.

Testing TCP port 110 on host mail.domain.com to ensure it's listening and open.

The port was opened successfully.

	Additional Details
	Elapsed Time: 198 ms.

The POP service is being tested.

The POP service was tested successfully.

Additional Details

Successfully tested the POP3 service
S: +OK The Microsoft Exchange POP3 service is ready.
C: CAPA
S: +OK
TOP
UIDL
STLS
.
C: STLS
S: +OK Begin TLS negotiation.
Secured: CN=mail.domain.com, OU=Domain Control Validated
C: CAPA
S: +OK
TOP
UIDL
SASL PLAIN
USER
.
C: USER test1
S: +OK
C: PASS <password>
S: +OK User successfully logged on.
C: STAT
S: +OK 22 239726
C: QUIT
S: +OK Microsoft Exchange Server 2016 POP3 server signing off.

Elapsed Time: 2575 ms.

Faris

Tuesday, February 19, 2019 6:29 PM

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While configuring outlook for IMAP or POP go to more settings and under advanced setting make sure outgoing server (SMTP) have port 25 selected and encrypted connection is none.

For incoming use secure (993 for imap and 995 for POP).

Thanks,

Ashish

MCITP, MCT, MCSE

“Tell me and I forget, teach me and I may remember, involve me and I learn.”

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Tuesday, February 19, 2019 6:45 PM

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Thanks for your reply.

If I choose the POP 995 and IMAP 993 for incoming connection and secure communication for outgoing is None. the outlook get connected, but may case i would choose to have TLS/SSL in outgoing connection- While choosing this option we are getting SMTP test error.

As per my knowledge should able to connect both SSL/TLS/None. selecting none option its allowing the clients to connect server using encrypted connection. Please correct me if am wrong.

Faris

Tuesday, February 19, 2019 9:30 PM

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Hi,

Did you followed below for secure SMTP.

https://docs.microsoft.com/en-us/exchange/clients/pop3-and-imap4/configure-authenticated-smtp?view=exchserver-2019

Thanks,

Ashish

MCITP, MCT, MCSE

“Tell me and I forget, teach me and I may remember, involve me and I learn.”

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Tuesday, February 19, 2019 10:18 PM

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I went through the article, i shared my output here, as below.

Faris

Tuesday, February 19, 2019 10:27 PM

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Hi,

Did you tried enabling anonymous users on client frontend receive connector security setting?

After that select TLS and put 587 in outgoing smtp setting.

Thanks,

Ashish

MCITP, MCT, MCSE

“Tell me and I forget, teach me and I may remember, involve me and I learn.”

Note:- Please remember to vote and mark the replies as answers if they help.

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Tuesday, February 19, 2019 10:57 PM

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Client Forntend Settings as per below. its seems already enabled

Faris

Wednesday, February 20, 2019 3:52 PM

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It should work then.

Do one thing while configuring outlook profile select server name in outgoing SMTP connection and select TLS with port 587. Let me result. Make sure no other authentication method is selected in advanced setting.

Also do a telnet from client to exchange server over port 587.

e.g. telnet ex1 587

Thanks,

Ashish

MCITP, MCT, MCSE

“Tell me and I forget, teach me and I may remember, involve me and I learn.”

Note:- Please remember to vote and mark the replies as answers if they help.

Disclaimer: This posting is provided "AS IS" with no warranties or guarantees and confers no rights.

Wednesday, February 20, 2019 4:05 PM

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i tried this way. am right ?
telnet response.
220 mail.domain.com Microsoft ESMTP MAIL Service ready at Wed, 20 Feb 2019 19:58:28 +0300

Faris

Wednesday, February 20, 2019 5:04 PM

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Exchange should accept connection now if certificate was assigned correctly.

Anyway. try this as well:-

Set-ReceiveConnector -identity "Ex1\Client front end ex1" -requiretls:$true

Replace connector identity with your connector identity which you can get by running get-receiveconnector.

Thanks,

Ashish

MCITP, MCT, MCSE

“Tell me and I forget, teach me and I may remember, involve me and I learn.”

Note:- Please remember to vote and mark the replies as answers if they help.

Disclaimer: This posting is provided "AS IS" with no warranties or guarantees and confers no rights.

Proposed as answer by Steve Fan Friday, February 22, 2019 9:52 AM
Marked as answer by Farispv Friday, February 22, 2019 8:06 PM

Wednesday, February 20, 2019 5:28 PM

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Hi Faris,

Any update here? Is the issue fixed now? Please don't hesitate to post back if further assistance is needed here.

Regards,
Steve Fan

Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

Click here to learn more. Visit the dedicated forum to share, explore and talk to experts about Microsoft Teams.

Marked as answer by Farispv Friday, February 22, 2019 8:06 PM

Friday, February 22, 2019 9:52 AM

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its not resolved yet, am searching the solvency.

Faris

Friday, February 22, 2019 4:47 PM

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I tried this but still not connecting. on TLS.

Set-ReceiveConnector -identity "Ex1\Client front end ex1" -requiretls:$true

Faris

Friday, February 22, 2019 5:03 PM

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Hi,

Can you please put server name (Ex1) instead of mail.domain.com and under user name put complete email address test1@domain.com?

After that test it.

Thanks,

Ashish

MCITP, MCT, MCSE

“Tell me and I forget, teach me and I may remember, involve me and I learn.”

Note:- Please remember to vote and mark the replies as answers if they help.

Disclaimer: This posting is provided "AS IS" with no warranties or guarantees and confers no rights.

Friday, February 22, 2019 5:12 PM

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I did Same. with my server name .

Glad to inform your,its finally worked, i have rearranged my firewall-rules. now its connecting on TLS.
but not connecting on SSL

Faris

Friday, February 22, 2019 5:21 PM

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Sounds Great....If you were able to do telnet then port should be open.

SSL is obsolute so use TLS only.

Also when Exchange install, it create all required firewall rules and enable those, so seems that either those were modified or somehow required rule was disabled.

Thanks,

Ashish

MCITP, MCT, MCSE

“Tell me and I forget, teach me and I may remember, involve me and I learn.”

Note:- Please remember to vote and mark the replies as answers if they help.

Disclaimer: This posting is provided "AS IS" with no warranties or guarantees and confers no rights.

Friday, February 22, 2019 5:30 PM

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Thank you very much for all of your support, may God Bless you.

The issue was my internal firewall rules priority.

Faris

Friday, February 22, 2019 8:05 PM

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Outlook not connecting POP3/IMAP clients SSL/TLS

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