A suppression list is a list of email addresses which have been suppressed from inclusion in commercial emails. Unsubscribing from a mailing list is a type of suppression opt-out mechanism that everyone is familiar with, but there are other modes of suppression as well.
Unsubscribe suppression takes place when a recipient directly opts-out of the mailing. This occurs generally through an unsubscribe link included in the email. It's helpful for senders to maintain a list of opt-outs in their own database or indicate for those contacts when they have opted-out of specific mailings. Sending to an email address which has already opted-out of your mailings is a bad practice and often leads to spam complaints, which can have a negative effect on your sending reputation and deliverability. Prompt suppression of unsubscribed email addresses is very important.
Hard bounce suppression occurs when a recipient email address hard bounces for a permanent reason, such as an invalid email address. When hard bounces occur, that means that email address is undeliverable, and we suppress these to discontinue sending to an address that is known to be undeliverable. Suppressing these email addresses helps to avoid inflated bounce rates or low delivery rates in future mailings by cleaning up the recipient list and eliminating undeliverable addresses.
What about soft bounces?
MessageGears will retry soft bounces (i.e.e mailbox full) for 24 hours. If the mail cannot be delivered, the email address will not be added to hard bounce suppression but will appear counted as a bounce within the specific job's activity stats.
As with unsubscribes, spam complaints should result in the email address being immediately suppressed. The primary difference between unsubscribes and spam complaints is that spam complaints carry extra weight and they express to the recipient's email service provider that the sender did not gain their permission to email them. High complaint rates are likely to cause you deliverability issues moving forward, and can be avoided by sending to a well-maintained recipient database based primarily on opt-ins. When a recipient knows who you are and why you're sending to them, they are unlikely to report your emails as spam.
Complaints are automatically handled by the MessageGears system through Feedback Loops with email and internet service providers. A complaint will immediately suppress that address for the Account the mailing was sent from. By maintaining a strict complaint suppression list, MessageGears helps to ensure that recipients aren't getting unwanted mail, while senders are made aware of issues with their sends in order to help with future deliverability.
With MessageGears, the system by default suppresses unsubscribes, hard bounces, and spam complaints at the Account level. Since we are an Enterprise solution, customers sending both marketing and transactional email in the same account can run into issues with the Account-level suppression lists for unsubscribes and hard bounces. Spam complaint suppression is always managed by MessageGears, but mirroring those opt-outs in your own database is important for the cleanliness of your data. When it comes to unsubscribes in particular, Account-level suppression can cause issues. Say a customer of your organization may want to unsubscribe from a marketing email, for example, but transactional emails like receipts or password resets are still important items for them to receive separately. In cases like this, you may choose to manage your mailing lists within your own database, including suppression. In such cases, you can work with MessageGears Support to customize your suppression settings.