While SmarterMail can run on a 32-bit system, it is not recommended as this can cause performance issues, such as running slowly or unexpected crashing.
The main reason for this is because a 32-bit system restricts the mailService.exe process to a very limiting 1GB of memory. Although small servers may run fine under 1GB, there are many small servers with a low number of mailboxes that could exceed 1GB of memory. For example, servers with users that have very large mailboxes and access them often. When a mailbox is accessed often, it is in memory more often, and when memory spikes that reach higher than this 1GB limit occur it can cause an un-catchable out of memory exception and cause SmarterMail to crash. Along with this, a 32-bit system has limitations on the number of threads, handles, and network connections that could negatively impact performance. Furthermore, SmarterMail is not the only thing that is limited. On 32-bit systems, Microsoft Windows itself is limited to the number of TCPIP connections it can maintain, and when it hits its limit, connections will be lost.
For the best performance, SmarterTools recommends running SmarterMail on a 64-bit system.