Email size estimates

For best practice, allow 1-3 MB per user per month when estimating the size of your Email Log Database.

For illustration, assume there will be 2 MB of data per user per month for 7500 users. Data will be kept for 3 months, with a scheduled monthly partition rollover.

Because rollover is monthly, it is necessary to allocate enough space to hold up to 4 months of data. (This ensures that it is always possible to report on 3 months of data, even during the first days or weeks of the most recent month.)

This means that you would need 60 GB to start:

2 MB * 7500 users * 4 months = 60 GB

In addition, you need to calculate space for the following:

  • The database transaction logs, whose size depends on the recovery model you choose.
    • For full recovery (not recommended), allow for the same size as the data itself (60 GB in our example).
    • For simple recovery, the log volume depends on the amount of database activity. Allow roughly 30 percent of the size of the available data.

      0.3 * 60 GB = 18 GB

  • Temporary database (tempdb) storage is used heavily during report generation. The amount of tempdb space required depends on the reports being run. As a best practice, allow the size of the logged data for temporary storage. In our example:

    60 GB

  • Temporary database (tempdb) transaction logs take up about 20 percent of the tempdb storage size. In our example:

    0.2 * 60 GB = 12 GB

The total space required in our example, then, is:

60 GB + 18 GB + 60 GB + 12 GB = 150 GB

Use the following tables to estimate storage space required for 30 days’ worth of data based on email volume.

  • The same requirements for partitions, logs, and temporary databases apply.
  • The estimates assume an average of 5 recipients per email message.

With the Forcepoint Email Security Hybrid Module enabled:

  10 msg/ user/day 50 msg/ user/day 100 msg/ user/day 200 msg/ user/day 400 msg/ user/day
500 users 600 MB 3300 MB 6600 MB 13300 MB 26700 MB
1000 users 1300 MB 6600 MB 13300 MB 26700 MB 53400 MB
2000 users 2600 MB 13300 MB 26700 MB 53400 MB 106800 MB
5000 users 6600 MB 33400 MB 66800 MB 133600 MB 267200 MB

Without the Hybrid Module:

  10 msg/ user/day 50 msg/ user/day 100 msg/ user/day 200 msg/ user/day 400 msg/ user/day
500 users 500 MB 2600 MB 5200 MB 10400 MB 20900 MB
1000 users 1000 MB 5200 MB 10400 MB 20900 MB 41800 MB
2000 users 2000 MB 10400 MB 20900 MB 41800 MB 83600 MB
5000 users 5200 MB 26100 MB 52200 MB 104500 MB 209000 MB

The calculations used are:

  • With the Hybrid Module:

    (0.01622+0.02348* RECIPIENT)* SPEED * USER

  • Without the Hybrid Module:

    (0.0384+0.01322* RECIPIENT)* SPEED * USER

Note that:

  • USER represents the total number of users.
  • RECIPIENT is the average number of recipients for each message.
  • SPEED is the average message volume for each user per day.

Note that the email hybrid service drops or blocks the following types of email before they reach on-premises components:

  • Email that comes from known bad (blacklisted) sources
  • Email that has a very high spam score in the cloud

This significantly reduces the amount of data stored in the Email Log Database, as shown in the examples above.