Fighting Mailserver Problems – Delivery Failed

First of all, check if the IP of the sending server is on any of the major blocklists:

• Proofpoint
• MXToolbox

Make sure you have the SPIF Settings for the sending domains set to the minimum security standard. For instance. Outlook.de requires at least something like this:

example.com IN TXT "v=spf1 a mx ip4:85.214.230.249 -all"

• Outlook Sender Policy Information
• Unblock Request for Microsoft Services

More Information:

• Hosteurope

Auch interessant: Zustellungprobleme bei Weiterleitungsadressen: Werden Sie nicht zur Spam-Schleuder:

• Infos bei Hosteurope