Cleaning out my cupboard I found an old container of Tetly herbal tea. I don't drink much herbal tea and had no idea of how long I had had this.

They send me back an email the next morning that was very useful

The shelf life of an unopened box of tea is approximately 2 years. The production code number indicates when the box/canister of tea was produced. If you have a canister, this number may be found on the bottom of the canister, and if it is a box, it is on the side panel of the box. For example, for the production code number that you have quoted, "3362", the "3" indicates the year, so the tea was produced in 2003. The "362" indicates that it was packaged on the 362nd day of the year (approximately December 28th). Therefore, the canister that you have
has passed its shelf life. Due to the sensitive nature of tea, once the box is opened (cellophane removed) the teabags themselves are very susceptible to picking up other odors or flavours. Therefore, in order to prevent the tea from becoming "tainted" by absorbing a foreign odour,
or from becoming "stale", we strongly recommend to our consumers that tea be stored in an air-tight canister mmediately upon opening, and placed in a cool, dry area.

This information allowed me to go through my tea stash and ditch most of it. I'm not in a phase where I'm drinking flavoured tea so there isn't much point keeping it around. When I buy it in the future I'll likely buy 2 or 3 individual bags from the bulk food store rather than box that I'm not likely to finish.

I didn't ask for a coupon or expect to get one - and I didn't.