What envelope specifications should I follow when printing on envelopes?

Envelope weight should not exceed 105 g/m² (28 lb) to avoid jamming. Prior to printing, envelopes should lie flat with less than 6 mm (0.25 in) curl and should not contain air. Make sure envelopes are not wrinkled, nicked, or otherwise damaged. Use envelope sizes from 90 x 160 mm (3.5 x 6.3 in) to 178 x 254 mm (7 x 10 in). Envelopes with double-side seams are more likely to wrinkle and may jam.