Email suppression lists, explained
A suppression list is the list of addresses you must not email again. Keeping it right is one of the simplest ways to protect your sender reputation.
Updated
What a suppression list is
A suppression list sits between your lists and your sends. Any address on it is skipped, whatever list or campaign it appears in. Unlike deleting a contact, suppression keeps the record of why the address was stopped, so a later import cannot quietly add it back.
Which addresses belong on it
- Hard bounces: the address does not exist or the domain does not accept mail. Sending again will bounce again.
- Spam complaints: the recipient marked your email as spam. Mailing them again is the fastest way to damage your reputation.
- Unsubscribes: the person asked to stop. Many laws require you to honour this promptly.
- Addresses you remove by hand, for example at someone’s request.
What about soft bounces?
A soft bounce is temporary: a full mailbox, a server that is briefly unavailable, a message that was too large. One soft bounce is not a reason to suppress. Repeated soft bounces from the same address over time usually are.
Why it matters for deliverability
Mailbox providers watch how many of your messages bounce and how many get reported as spam. Sending again to addresses that already bounced or complained pushes both numbers up, and a high bounce or complaint rate can send even your good emails to spam.
Suppression keeps those numbers low automatically, without anyone having to clean lists by hand before every send.
Suppression and list imports
The most common way suppressed addresses come back is an import: an old spreadsheet or a CRM export that still contains them. A suppression list that applies at send time catches them, wherever they come from. Validating a file before you import it catches the rest: typos, disposable addresses and role addresses such as info@.
Suppressions in LumySend
In LumySend, hard bounces, complaints and unsubscribes go on the suppression list by themselves, and suppressed addresses are skipped in every later send. You can also validate a CSV, TSV or Excel file before importing it: LumySend flags duplicates, disposable and role addresses, likely typos and gives each address a risk score.
Each message keeps its own timeline, from queued to delivered, opened and clicked, so you can see what happened to every send.