Brother MFC-890 User Manual page 37

Do not use paper or envelopes:
that are damaged, curled, wrinkled, or irregularly shaped
that are extremely shiny or highly textured
that were previously printed by a laser printer
that cannot be arranged uniformly when stacked
that are made with a short grain
Do not use envelopes:
that are of a baggy construction
that are embossed (have raised writing on them)
that have clasps on them
that are not sharply creased
that are preprinted on the inside
2 - 4 PAPER