Side note - if it's just emails you're worried about, you can start by just sending the emails with any timezone - the header should automatically be adjusted by the client. For times inside the email, check out Time::Zone - rather than adding 4*3600, try tz_offset('...') where '...' is the timezone you want your output to be in.

Perhaps one of the more experienced pmdevils here would know how PM handles the same situation since everyone can specify the timezone they want to see stuff in.