DateTimeHelper::ParseRFC2822DateString integer overflow on 32-bit PHP (getTimestamp() fails)

[sgoranov]

Description

On a 32-bit PHP version, getTimestamp() in DateTimeHelper::ParseRFC2822DateString() fails with:

PHP Fatal error: Uncaught Error: Epoch doesn't fit in a PHP integer in Messages.php:101

This happens because getTimestamp() returns an integer, which exceeds the 32-bit limit for large timestamps.

Steps to Reproduce

1. Install SnappyMail on a 32-bit PHP system (e.g., Raspberry Pi).
2. Attempt to parse an RFC 2822 date string with a large year (e.g., Thu, 10 Jun 2038 08:58:33 -0700).
3. Observe the fatal error.

Expected Behavior

• It should not crash on 32-bit PHP.