Forum Discussion
550 5.7.515 Access denied
I just started getting (100%):
"550 5.7.515 Access denied, sending domain xxxxx.xx doesn't meet the required authentication level"
when sending emails to hotmail addresses using Outlook desktop for Windows ("classic", 365 MSO - Version 2607 Build 16.0.20228.20124) 64-bit).
This was working just fine up until some time ago. Other email domains works just fine. Using the same ISP.
Other email clients (Gmail, webmail) works fine. It only fails when using Outlook to send.
Spf= Pass , Dkim= Fail , DMARC= Pass
I am using SMTP, have tried both port 465 and 587 (STARTTLS and SSL/TLS). Using the same credentials as for sending emails (POP) as required by the ISP (no changes here).
Any way to fix this?
The rejection is caused by sender-domain authentication, not the Outlook port or password. Microsoft’s 5.7.515 response means the domain in the visible From address did not meet Outlook.com’s required authentication level. Your result already shows the key clue: DKIM fails. Webmail or Gmail can work because they may use a different outbound server, DKIM signer, return path, or From domain. Send one test from Outlook and one from webmail, then compare their Authentication-Results, From, Return-Path, and DKIM d= values. Ask the ISP or domain administrator to enable valid DKIM signing on the SMTP service used by Outlook and verify that its domain aligns with the From address. Also confirm SPF includes that outbound service and that a valid DMARC record exists. Port 465 versus 587 will not repair DKIM. If you do not control the domain’s DNS or mail server, only the provider can correct this.
2 Replies
Thank you for the detailed response! I will contact my provider.
The rejection is caused by sender-domain authentication, not the Outlook port or password. Microsoft’s 5.7.515 response means the domain in the visible From address did not meet Outlook.com’s required authentication level. Your result already shows the key clue: DKIM fails. Webmail or Gmail can work because they may use a different outbound server, DKIM signer, return path, or From domain. Send one test from Outlook and one from webmail, then compare their Authentication-Results, From, Return-Path, and DKIM d= values. Ask the ISP or domain administrator to enable valid DKIM signing on the SMTP service used by Outlook and verify that its domain aligns with the From address. Also confirm SPF includes that outbound service and that a valid DMARC record exists. Port 465 versus 587 will not repair DKIM. If you do not control the domain’s DNS or mail server, only the provider can correct this.
