550 “Asked Not to Receive Your Emails”
This email rejection is generated when a recipient flags your message as spam via their inbox (for example, when they click the 'Report Spam' button in Yahoo). Once notified, SMTP2GO automatically blocks future outbound attempts to the recipient.
You can find these rejections (called 'rejects') by visiting the “Reports > Activity” section of your SMTP2GO account’s dashboard.
Please note that you may need to adjust your search filter in order to locate a reject, or the original spam complaint.