I sent an email to an acquaintance on Monday and he didnt respond, and I thought that's a bit rude.
Turns out he probably hasnt received it as I just got this last night ...
Reporting-MTA: dns; mailfilter2.ihug.co.nz
Final-Recipient: rfc822;"friend"@btinternet.com
Action: failed
Status: 5.0.0 (permanent failure)
Remote-MTA: dns; [65.20.0.49]
Diagnostic-Code: smtp; 5.4.7 - Delivery expired (message too old) [Default] 421-'Too many messages (1.5.7.2) on 2017/06/08 11:30:04 BST from un-validated IP address: 203.109.136.2. Please add a SPF record for the domain vodafone.co.nz to your DNS or ask your Broadband Provider / Domain Registrar to do this, we will be unable to deliver email until this is done due to the volume of email being sent from this IP address. Guide for bulk senders www.bt.com/bulksender' (delivery attempts: 76)
Am I the bulk sender?