Outlook 2013 cannot send email ("Message rejected under suspicion of SPAM", error 554)

Question

I have been using a POP3 account in Outlook 2013 to download and send email for some time without any problem. Recently I have setup a new POP3 account and am having difficulty sending email.

The account requires the following server settings:

POP3 server — 995;
SMTP server — 465.
SSL encrypted connection connection enabled

All settings & passwords have been verified as correct and a test mail can be sent successfully from within the account setup dialogue.

The difficulty comes in sending a real email. Whenever a real email is sent Immediately a response is given by Outlook in the form of an email from the "System Administrator". There is no Mailer Daemon rejection and no message headers because the email is not even being sent. I do not even have a system administrator, it is just me on my Windows 8.1 PC connecting to the internet via a commerical domestic ISP.

The delivery failure message from the "System Administrator" reads as follows:

Your message did not reach some or all of the intended recipients.

  Subject:    Postal address
  Sent:   25/04/2015 12:03

The following recipient(s) cannot be reached:

 '[email protected]' on 25/04/2015 12:03
        554 5.7.1 Message rejected under suspicion of SPAM 1429959803-NUeir8yQC4-3N5Su25a

The code after the word "SPAM" changes every time.

The problem has been documented here: http://www.emailquestions.com/isp-free-email-support-forums/10024-yandex-mail-paranoid-side-spam-detection.html and elsewhere.

I have tried the following to no avail:

1. Sending a message to different email addresses.
2. Enabling logon with secure password authentication (SPA) in account settings.
3. using a different port number for the outgoing server and connecting without encryption.
4. disabling firewall and antivirus

Could it be that Outlook 2013 has a blacklist built into it and will just not allow email to be sent via some SMTP servers?

Thank you in advance for your help.

Hajji

Answer 1

One of the difficulties here is establishing whether the message is coming from Outlook, or from the SMTP host. Other mailclients tend to be more informative, and a test with Pegasus or Thunderbird might shed some light. Or, do a test by telnetting directly to the SMTP host.

The 'System Administrator' is Outlook itself, BTW.

A common issue is that you might have changed the SMTP setting to a host outside of your ISP's IP address range. In that case, you will either be rejected outright, or will need to authenticate. SMTP Auth is under the advanced account settings. Try turning it on. In most cases the option to use the POP3 logon will work.

Another area to check is antivirus plugins which intercept outgoing mail.

Also, do not overlook the possibility of a typo in your contacts. I've seen a space in the email address cause this.