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how_to:install_vpop3

How to Install VPOP3

Simply download VPOP3 from the website, and run the installation program and follow the prompts.

Occasionally people may have problems with the PostgreSQL part of the installation. If that happens, please contact us either by email at support@pscs.co.uk or by phone to +44 (0)1484 855800, and we will do our best to help.

If this is an initial installation, then you can call 0871 311 1047 (calls cost 10p per minute from a BT land line) and we can remote into your server to help you configure it. Note that this service is not available for reinstalls/moves etc. See other articles on this Wiki, or use our normal support methods.

Some problems which have occurred during installation

Things to consider

Disk Caching

You may need to turn off disk write-back caching on your PC. Database systems require tight control of hard disks to avoid disk corruption. Write back caches will pretend to write data to the disk before actually doing so. This means that if the PC is turned off (or explodes or the power fails) between the cache pretending to have written the data and it actually being written, the data will be lost, and this can cause the database to be corrupted.

  • You should definitely disable write-back caching if your VPOP3 computer does not have any protection method such as a UPS with automated shutdown software. In this case, a power cut or glitch will cause the PC to reboot, possibly corrupting the database.
  • You should consider disabling write-back caching if your VPOP3 computer has a UPS with automated shutdown software. In this case you will normally be OK with a power cut, but if the UPS fails or the PC doesn't shut down properly before the power fails, you may corrupt the database.
  • You should be OK if you have a disk controller with a battery-backed write cache (BBWC). Most server PC hardware (other than very low end) will have this type of cache (usually as part of a hardware RAID controller), as it improves performance whilst allowing safe use of the caching. This type of cache will store the cached data until the PC is restarted, when it will be written safely back to the disk.

To disable write caching:

  • If you have a RAID controller, check the settings for that.
  • In Windows, go to the Disk Drives section of the Windows Device Manager, right-click the hard disk where VPOP3 is installed, and choose Properties then go to the Policies tab. If there is an option in there called Enable write caching on the device (or similar), then turn it off. On some versions of Windows this may have a different name but the text on that property tab usually explains the options.

Note that if you disable write-back caching then you will slow down the disk access on the PC, so the choice is really yours whether you prefer the speed of having it enabled or the safety of disabling it. Using server PC hardware with battery backed cache is the best option if you need both the speed and the safety.

Note that if write-back caching is turned off, then if the power fails, the PC explodes etc, then the data written to the database is automatically recovered when the PC is restarted, but if write-back caching is enabled, this can defeat the recovery process which won't have accurate checkpoint data.

Antivirus Programs

We recommend that the VPOP3\pgsql\data folder is excluded from any virus scanning. That is because if any of the data files in these directories contain anything which the virus scanner considers suspicious it may delete or quarantine a database file, and thus trash the database completely, needing a database restore from a backup, and probably losing some messages.

Desktop virus scanners often have email virus scanning capability. These often cause problems if run on a mail server itself (that is not what they are designed to do). We recommend that if you encounter any problems with sending or receiving mail, you turn off the email scanning part of the virus scanner on the VPOP3 computer to see if that is the problem. If it is, then you can use one of our integrated virus scanners such as VPOP3 Antivirus, use a third party virus scanner specifically designed to run on a mail server, or rely on the virus scanner on the users' PCs.

Some virus scanners include a firewall/Internet security component. If you use one of these, then you need to be prepared to configure the firewall to allow VPOP3 to act as a service for your network. We cannot provide support for this (except for the standard Windows firewall) as part of our free email support service. You should contact your antivirus/firewall vendor for help, or use one of our paid support options.

Backup Programs

If you have a backup (or disk duplication/synchronisation) program running on the VPOP3 computer, make sure it does not backup the VPOP3\pgsql\data folder. If the backup program is backing up that folder and is backing up a database file at the same time that the database server is trying to access it, it can lead to a corrupted database.

This is especially the case if you have a 'continuous backup program', which is far more likely to cause problems because of the constant changes in those folders.

However, if the backup program uses the Windows VSS (Volume SnapShot) system, then it is safe to use on those folder.

VPOP3 does periodic backups of the database (by default into the main VPOP3 folder), so backing up those database backups is sufficient to allow you to restore the database to the time of the latest database backup.

Disk Quotas

If the computer running VPOP3 has 'disk quotas' set, make sure that both the account which the VPOP3 service runs as (default 'Local System') and the PostgreSQL database runs as (default 'postgres') have sufficient space to store their data.

If the 'postgres' user's quota runs out, then incoming messages may be lost as VPOP3 has nowhere to store them.

Other

how_to/install_vpop3.txt · Last modified: 2018/11/14 10:45 (external edit)