my friend ask me to help because he cannot send email from his company. i just have little knowledge about mail server so what i do:

dig mx hiscompany.name

then try to send using telnet with port 25 no answer.

telnet mx.hiscompany.name 25

then try to send using telnet with port 587

telnet mx.hiscompany.name 587

it return

Connected to mx.hiscompany.name.
Escape character is '^]'.
+OK POP3 server ready <d9-4b15-4466-8dbf-9ce7a2a2@server03.aa.b>

so is this mean that there is misconfiguration somewhere or what. because that header is like telnet to pop3 port 110? i can use command user and pass just like telnet to pop3 port.

then i just run nmap hiscompany.name and i cant seem to find any smtp this is what scan return

110/tcp   open  pop3
|_pop3-capabilities: USER IMPLEMENTATION(Smartertools SmarterMail 1 5) UIDL APOP TOP OK(K Capability list follows)
| banner: +OK POP3 server ready <d9-4b18-4466-8dbf-9ce7a2a2@server03.aa

587/tcp   open  submission
|_smtp-commands: SMTP: EHLO -ERR Invalid command
| banner: +OK POP3 server ready <d9-4b15-4466-8dbf-9ce7a2a2@server03.aa

please some one tell me that there is somehow problem with the server configuration or something because he said that his IT person say there is no problem with the server.

EDIT I ask my friend to try login using webmail instead of mail client like outlook he said he can send and receive when using webmail. ok so i really dont understand.

  • You need to check that the firewall is allowing network connections from anywhere into port 25 on the server. It's not a server problem, it's a firewall problem. – mauvedeity Sep 23 '11 at 19:13
  • Their technical person ask to use port 587 for smtp and 110 for pop3 to configure email client when i try it still retun same error (can receive email but cannot send). and i ask if they use port 25 or perhaps any other port they say nope its 587 for smtp. :-] – user95717 Sep 23 '11 at 19:31
  • OK, your question hasn't gotten slightly confusing. Can you add an edit with the output from the following 3 telnet sessions: 1. telnet his.company.name 25, 2. telnet his.company.name 110, 3. telnet his.company.name 587 – joeqwerty Sep 23 '11 at 19:34
  • Well, their IT person is mistaken, because that is definitely a POP3 server answering on 587. It's acceptable, and not uncommon, to ask email clients to use 587 (particularly because some larger ISP's block port 25). I would tell your friend to tell his IT guy to telnet to port 587 from 'the outside world' and see for himself. – Coding Gorilla Sep 23 '11 at 19:39
  • Also, your friend will need to modify the configuration of his email client to tell it to use port 587 for "Outgoing Email" or SMTP, instead of the default configuration of 25. – Coding Gorilla Sep 23 '11 at 19:40

You analysis seems correct; it doesn't seem like there is an SMTP server listening. Even if an SMTP server was listening on 587, he would still not be able to receive email from the outside world. MTA's will only be connecting on port 25, while some clients may be purposely configured to use 587.


You will need to tell your friend to telnet port 25 from 'inside' his firewall, and once his server is running SMTP on port 25, to check his firewall.

I suspect your friend will have to play politics with his IT person, so he tells him what the email setup is supposed to be and who is responsible for firewall setup and email support...


It's not a firewall problem, it's a misconfiguration problem.

Look at the server announcement, it clearly states it's a pop3 server NOT an SMTP server.

Your friend has the server thats used to log in and check to receive mail running on port 25 (Should be port 110) and where the SMTP server is listening is anyones guess.

  • 1
    Look more closely, that's responding to port 587 (smtp submission) and 110. – Coding Gorilla Sep 23 '11 at 19:23
  • 1
    Exactly my point!! He has the POP3 server set up to respond to the 2 ports that he's expecting a response from on the SMTP service. Now if this was down to the firewall, it's NOT a firewall problem, but a firewall mis-configuration because the port forwarding has clearly been set up to route 25 to 110 and secure smtp to 587. Firewall problems don't miraculously pick the opposite or counterpart server to the service your connecting. – shawty Sep 24 '11 at 10:17

protected by Community Sep 23 '11 at 21:05

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.