Description of Suppression List Types

  • Database Suppression List: Stored in the Pexicast database, this list contains recipients to whom you do not wish to send mail. The format of this data is identical to the above list type, and, in addition, all the same types of imports apply. This type of list should not be used for large sets of data (Must be kept SMALLER than 100,000 records).
  • File Suppression List: This suppression list is loaded from a file within your FTP directory, (see instructions for how to upload via FTP) in a subdirectory named ‘suppression’. The file must consist of email addresses, one per line, in the format specified below. Any email address which appears in this file will not be mailed to, as long as the address is an exact match. For example, if the file contains annabel@optimum.com then she would be suppressed, but annabel@yahoo.com, annaliz@optimum.com and annabel@optimum.net would still get mail.
  • File Domain Suppression List: This suppression list is loaded from a file within your FTP directory, in a subdirectory named suppression. The file must consist of domain names, one per line, and the file should be in the format specified below. Each domain name may be in one of three forms:
    • @domain.com: Email addresses going exactly to the specified domain will be suppressed. For example, if @yahoo.com were specified, then no mail would be sent to jim@yahoo.com or jane@yahoo.com, but mail would still get through to jeff@mail.yahoo.com.
    • .domain.com: Email addresses going to any subdomain of the specified domain will be suppressed. For example, if .rr.com were specified, no mail would go to andy@newyork.rr.com orliz@virginia.rr.com, but mail would still go out to james.q.smith@rr.com.
    • domain.com: Email addresses going to any subdomain of the specified domain will be suppressed. For example, if rr.com were specified, no mail would go to andy@newyork.rr.com, liz@virginia.rr.com, orjames.q.smith@rr.com. This is the same effect as if there were two lines, @domain.com and .domain.com right after each other.
  • File Username Suppression List: This suppression list is loaded from a file within your FTP directory, in a subdirectory named ‘suppression’. The file must consist of usernames (the part up to and including the @ of an email address), one per line, and the file should be in the format specified below. Each username may be in one of two forms:
    • user@: Any email to anyone whose username is user will be supressed. For example, if bill@ is specified, no mail would go to bill@yahoo.com or bill@gmail.com, but mail will still go to billg@microsoft.com.
    • user: Any email to anyone whose username starts with user will be suppressed. For example, if steve were specified, neither steve@apple.com nor stevey_wonder@hotmail.com would get mail, althoughlittlesteve@abc.com would not be suppressed.
  • File Keyword Suppression List: Regular expression (Java-style) file-suppression list. Contact technical support for more details, if you wish to use this facility.
  • File MD5 Suppression List: an MD5-hashed suppression list. Each row of the input file should be an MD5 hash code in hexadecimal format, with an optional 0x prefix. Each hexadecimal number should be 32 characters long, meaning it should be a 16-byte number. Any invalid records will be silently skipped.

Email addresses are first "normalized" (per ESPC guidelines) before being MD5 hashedchecked against this list. Normalization is done as follows:

  • All whitespace is removed from the email address
  • The email address is converted to lower case

Please note that this service always converts any e-mail address to lower case anyway, and that whitespace in an email address is not valid either, so in most cases the normalization will not result in any different behavior.

THINGS TO BE AWARE OF:

Any of the suppression lists may be used when creating jobs to prevent mailing to addresses found within the suppression lists.

All of the file-based suppression list files must be in plain text, ASCII format, with no lines longer than 64 characters.

Note that all email addresses are treated completely case insensitively, so suppressing mail to BILL will stop mail from getting to bill, Bill, or even BILL.

The list type may not be changed once the list is created.

USAGE NOTES:

Advantages of using File Suppression Lists over Database Suppression Lists include:

  • Much easier to update the list: simply update or replace the file
  • No need to import, which can be a slow procedure
  • Ability to use larger suppression lists (larger than 100,000 entries)
  • Jobs build faster

On the other hand, some advantages of using Database Suppression Lists over File Suppression Lists include:

  • Ability to search the suppression list online
  • User interface to add and change entries online
  • Ability to move or copy records into these lists using rules

In general, we recommend the use of File Suppression Lists when possible, except for the smallest suppression lists, which certainly can be handled by Database Suppression Lists.

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