This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Cannot Send email - SMTP error for Office 365

  • 1 ŋuɖoɖo
  • 1 masɔmasɔ sia le esi
  • 13 views
  • Nuɖoɖo mlɔetɔ Matt

more options

I have configured the email account correctly, following the office 365 suggestions and set the port to 587, security set at STARTTLS, yet it gets me this error.

Sending of the message failed. An error occurred while sending mail: Outgoing server (SMTP) smtp.office365.com is unknown. The server may be incorrectly configured. Please verify that your Outgoing server (SMTP) settings are correct and try again.

The funny thing was this happens from time to time, sometimes I could send an email out with no problem, but sometimes I got this.

Any help would be appreciated. Thanks!.

I have configured the email account correctly, following the office 365 suggestions and set the port to 587, security set at STARTTLS, yet it gets me this error. Sending of the message failed. An error occurred while sending mail: Outgoing server (SMTP) smtp.office365.com is unknown. The server may be incorrectly configured. Please verify that your Outgoing server (SMTP) settings are correct and try again. The funny thing was this happens from time to time, sometimes I could send an email out with no problem, but sometimes I got this. Any help would be appreciated. Thanks!.

All Replies (1)

more options

I blame DNS. after all if the server is unknown it is because DNS has not located it.