Most email providers cap attachments at around 20–25 MB, and scanned or image-heavy PDFs blow past that easily. The good news: the bloat almost always comes from one place, and it's fixable in a minute.
Text is tiny. What makes a PDF huge is images — photos, scanned pages, screenshots embedded at full camera resolution. A single phone photo can be several megabytes, and a scanned contract is really just a stack of images. Shrinking those images shrinks the file.
Re-encoding the embedded images at a sensible quality typically cuts a photo-heavy PDF by half or more, with no visible difference on screen or in normal printing. pixelpix's PDF compressor does exactly this in your browser, and it's honest about it — if a document has nothing compressible, it tells you instead of pretending it shrank.
The PDFs people most often need to email — contracts, tax forms, medical letters, bank statements — are exactly the ones you shouldn't upload to a random "compress PDF" website. pixelpix processes the file entirely on your own device, so a private document stays private while you shrink it.