So, I have to wear a white or black shirt to work. White is not a good color for sweaty-armpitted coffee drinkers. Bleach pens are great for my polo shirts, but what about that linen blouse that’s turning gold in the armpits?
(Yeah, I know, I could just buy more black shirts, but I still have a lot of white ones from a job where I was only allowed to wear white!)
Try Yellow Out. I think that’s the name, but it’ll be in with all the detergents and the like.
Lucky for you, linen is fairly sturdy.
First, check your ventilation. Or at least check your laundry soap box for warnings about mixing with ammonia.
Then, make a paste of plain ammonia (not sudsing) and powdered laundry soap. Apply to icky part of shirt – rub in thoroughly but gently. Let sit for 5 minutes, & rinse. Do it again if necessary, 5 minutes at a time. Wash as usual, but check before drying. Dryers make nasty stains permanent. After rinsing well (do NOT mix bleach and ammonia – that makes major bad juju) try the bleach pen, or make a paste of bleach & laundry soap. rinse, repeat.
Then Google Hints from Heloise.
Then give up & buy new shirts.
Let the shirt soak for a few hours in water with a few scoops of Oxyclean.
Does the trick every time.
a good soak in 20 mule team borax mixed with amonia works well also.
I haven’t seen a stain that fels-naptha couldn’t remove.
Considering that I ended up high as a kite last time I used bleach to destroy a pair of jeans… that may be the best advice yet. :>
Thanks, you guys. 
White vinegar is also supposed to work well. I’ve never tried it, so I can’t say from personal experience.