Make sure to check if the envelopes to be used are supported by this printer.
Check there is no air in the envelopes before loading.
Load only one size and type of envelope at a time.
Before loading envelopes, flatten their leading edges (the edge going into the printer) by running a pencil or ruler across them.
Some kinds of envelope might cause misfeeds, wrinkles or print poorly.
Print quality on envelopes may be uneven if parts of an envelope have differing thicknesses. Print one or two envelopes to check print quality.
In a hot and humid environment, the envelope might be output creased or improper printing quality.