I will use this an a agent, i will remove documents that older than 10 minutes from @Now.The field mailDate creates when you save the document for the first time. I use @Now in that field.
years:=0;
months:=0;
days:=0;
hours:=0;
minutes:=10;
seconds:=0;
tmp := @Adjust( mailDate ; years ; months ; days ; hours ; minutes ; seconds);