As above really. Is it once stamped/post marked? After it goes into a letter box? Or as soon as you seal the envelope?

If a letter is put in the tray to go to the post room but is not stamped/post marked, can the post room legally open it and, say, put it into a different envelope?

Legally, probably after it is in the hands of the postal company (Including the letter box)
Morally, as soon as you seal it.

If it's not left the company, I'd say they're entitled to do whatever they like with it.

Personal mail sent via employer?

if it's on company business then anytime unless it's marked private and confidential etc.

it it's personal mail and you know it is then you can't open it.

I found this,

http://www.legislation.gov.uk/ukpga/2000/26/section/84

Section 84 explains that it's (paraphrasing) illegal to open a letter "in the course of its transmission by post," which isn't hugely specific.

cynic-al – Member
Personal mail sent via employer?

No, people using the 'wrong' sized envelopes. e.g. ones which look A5 but aren't. The mail room are opening the larger envelopes and putting them into smaller ones to save money. You have to pay someone to do it, and you waste and envelope – not to mention the ethical and legal issues – but apparently if it appears to save money it is ok.

I've just spoken to an ex-cop who says it becomes illegal after the mail has entered the Royal Mail system – so once in a post box or equivalent.

f a letter is put in the tray to go to the post room but is not stamped/post marked, can the post room legally open it and, say, put it into a different envelope?

I'd suggest yes, at that point it's merely a piece of paper in an envelope rather than a "postal packet".

If it's personal mail then the company could be seen to be in breach of your 'right to a private life' by opening it (albeit they could accuse you of theft if you put personal post in the company post).

I guess the lesson is don't put pr0n in the internal mail…

No, people using the 'wrong' sized envelopes. e.g. ones which look A5 but aren't

Perhaps your employer would be better off issuing staff with the right sized envelopes to start with.

If it's company mail they own it, until it leaves their care, and event after that with disclaimers etc.

There is no such thing as personal mail in a company mail system, the same applies to email.

If it's personal take a walk at lunchtime and post it.

There is no such thing as personal mail in a company mail system, the same applies to email.

Interesting reading on this here:

http://www.adviceguide.org.uk/index/life/employment/monitoring_at_work.htm