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Outlook cannot connect to your mail server ?

When setting up Outlook, or after ISP network changes, it is a common annoyance to be unable to send/receive email with a message of this type:

"Outlook cannot connect to your outgoing (SMTP) e-mail server. If you continue to receive this message, contact your server administrator or internet service provider (ISP)."

Navigate to your email account settings in Outlook under: Tools > Account settings > highlight your account and click "change" > click "more settings"

Look through all the tabs. Make sure the outgoing/incoming mail servers, your username and password are correct.

Under "Outgoing Server", make sure you check: "My outgoing server (SMTP) requires authentication" and "Use same settings as my incoming mail server"

In the "Advanced" tab:
Select the correct type of encryption, and the correct ports for "Incoming server" (usually 110) and "Outgoing server (SMTP)" - 25 is the default outgoing port, however, many major ISPs block this port to reduce outgoing spam, so if you're not using your ISP for email, it may be blocked and that is probably the culprit. As an alternative, try port 2525, or one of the secure ports below.

Here is a list of the default standard mail ports for your reference:
SMTP - port 25
POP3 - port 110
POP3S (POP3 over SSL, SSL-POP) - port 995
IMAP - port 143
IMAPS (IMAP4 over SSL) - port 993
SMTP mail submission - port 587
SMTPS (Secure SMTP, SSMTP) - port 465

You can also try scanning the above ports to see which one is open on your mail server using our portscan, and/or you can also contact your ISP to verify whether they are blocking any mail ports, port 25 is the most common one being blocked.

Instead of a portscan, you can also try testing if a port is open on a specific host by doing the following:
1. Open Command Prompt (Start > Run > type: cmd)
2. type: telnet hostname 25 (where hostname is the exact name of the SMTP server, and "25" is the port you'd like to test)
If your ISP (or your firewall) is blocking the port, you will not be able to connect. If you can connect to the port, it indicates some other Outlook configuration issue, even though it can still be a firewall/anti-virus software problem.

Residential ISPs often block outgoing mail ports for outside mail servers (that don't belong to that provider), like ports 25, 465, 587. Some mail servers are configured to also use port 2525 as an alternative to 25 unofficially.
It is also possible that your software/hardware firewall is configured to block some of the above ports, reconfiguring it or turning it off temporarily may help troubleshoot.

  User Reviews/Comments:
by anonymous - 2014-04-17 00:49
Tks you very much! It's very helpful!
by Tien - 2014-09-03 10:47
Thank you very much
by anonymous - 2015-03-22 15:34
Sorted! I couldn't ask for more.
by anonymous - 2015-07-27 11:22
Super! In my case, I found out that my mail host use port 25 and 587. So by swapping to 587 in Outlook settings I managed to fixed the outgoing emails.
by Sabbir - 2015-09-16 01:54
by anonymous - 2015-09-23 15:21
Thank you so much that was a huge help!!!
by anonymous - 2015-12-08 15:37
perfect fix. Thank you for being a helpful netizen, much appreciation
by Vinit - 2016-01-08 04:15
I tried all the possible settings. Checked my internet speed also but still i'm receiving the incoming server error and continuously prompting a pop-up to re-enter the Login name and Password!
Thank you
by Sandra - 2016-01-29 21:37
Thank you so much for your help. I have been wrestling with this problem all day. I used 587 instead of 25...fixed the problem. Bless You!!
by Ruchi - 2016-03-04 00:28
I am getting a incoming and outgoing error. The standard one. However, i dont get this when i am at home. Please note that there is no proxy server at either place.
btw, i migrated from Windows 8.1 to Windows 10 and this problem has been coming since them (only at work)
by Philip - 2016-03-05 09:14
Most likely your employer is blocking those ports for external mail servers.
by Matt - 2016-03-23 19:15
what if your ISP gives you the exact settings and you set them up exactly as instructed five times and you still can't connect?
by Jollie - 2016-03-24 06:31
Tried it all still not working. ISP is Telkom, do you think the problem lies with them?
by Philip - 2016-03-24 09:11
It is possible that the problem is with your ISP.

Once you know the exact hostname of your SMTP server, you can test in command prompt as detailed above whether the correct port is open.

The port being closed indicates it is blocked by your ISP or firewall. The port accepting connections indicates software/configuration issue, so you can determine which it is.
by anonymous - 2016-04-12 06:56
Thank you so much. Had to change my smtp port to 587 and now everything works perfectly. Have been fighting with this issue for several days now and was getting ready to pull my hair out :-)
by anonymous - 2016-04-21 15:51
I have been struggling with this all day. Literally like 7 hours of reading a bunch of wesites with instructions. Once I read this site it took me less than 3 minutes and ALL DONE! Can't thank you enough!
by anonymous - 2016-08-31 22:46
by anonymous - 2016-10-09 19:28
Thanks ^_^
by Sachin - 2016-10-26 08:53
Not worked for me even after trying to switch to all ports , anyone please suggest solution for me contact no. 7350780991 its urgent , I am only getting emails in Inbox but unable to send the emails
by Flash - 2016-11-24 05:48
Thanks so much. Yes I think that port 25 had been blocked by the server so I tried 587 and it WORKED. This was of course after two hours on the phone with tech help.
by anonymous - 2017-02-17 11:37
I have tried the ISP and they said that they cant do anything about it. Spoke to the my mail provider and they said there is no issue on the server. And the webmail seems to be working fine. Tried changing the ports as well but still no luck. Wondering if its the firewall? How do i change settings on there for the mail?
by Jayakrishna - 2017-05-17 14:57
Hi I tried all the above options but still getting the same error.
by anonymous - 2017-08-18 14:10
That worked for me! Thanks a lot for sharing your tip.
by anonymous - 2017-08-22 22:18
Thanks. My problem was the 587 was block. We use 465 then OK
by anonymous - 2017-12-13 22:52
THANK YOU! This fixed my issue.
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