Feedback Loops (FBL) automatically handle recipients who mark your emails as spam. When someone clicks "Report Spam," the mailbox provider forwards the complaint to an email address you've registered with their FBL program. Mumara checks that mailbox, finds the complaining contact, and flags them as Spammed — they will not receive any further emails from the system. You manage FBL addresses under Setup → Feedback Loops.
Setting one up works much like a bounce address: click Add New and enter the FBL email address, the IMAP or POP3 server hostname, port (typically 993 for IMAP over SSL), username, password, and mailbox folder (default INBOX). Choose SSL/TLS encryption, optionally delete emails after processing (recommended to avoid duplicates), and click Validate Connection before saving. You also need to register the address with each ISP's program — for example Yahoo/AOL's Complaint Feedback Loop or Microsoft's JMRP. Gmail has no traditional FBL; use Google Postmaster Tools instead.
On the list page, click the Complaints number for any FBL address to see processed complaints with the contact, the campaign or trigger that caused it, and the complaint time. Flagged contacts appear under Lists & Contacts → Suppression.
Worth knowing: the Spammed flag is permanent — never re-add complainers; aim for a complaint rate below 0.1%; and if complaints stop processing, check that the FBL status is active and the system cron is running.