Dictionaries are useful. With a small effort, You could have answered your own question immediately. The Oxford Learner's Dictionaries are an excellent resource for non-native speakers. bulge verb https://www.oxfordlearnersdictionaries.com/definition/american_english/bulge_1?q=bulge [intransitive] bulge (with something) (usually used in the progressive tenses) to be completely full (of something) Her pockets were bulging with presents. a bulging briefcase bulging line verb https://www.oxfordlearnersdictionaries.com/definition/american_english/line_2 cover inside [often passive] line something (with something) to cover the inside of something with a layer of another material to keep it clean, make it stronger, etc. Line the pan with aluminum foil.

“Lined with” means that the heroin is in between two layers of something else — Here, the heroin is apparently somehow slipped in between the layers of paper that make up the postcard. “Bulging” means so full that the sides of the mailbag are pushing outwards, barely able to contain the mail that is inside.