Square Envelopes2 3/4 x 2 3/44 1/4 x 4 1/45 x 55 1/2 x 5 1/26 x 66 1/2 x 6 1/27 1/2 x 7 1/2 Home > Envelopes and Liners > Square Envelopes Square Envelopes Please note : All square envelopes require additional postage when mailing. Sizes 2 3/4 and 4 1/4 are not mailable. 2 ¾ x 2 ¾ 4 ¼ x 4 ¼ 5 x 5 5 ½ x 5 ½ not mailable not mailable 6 x 6 6 ½ x 6 ½ 7 ½ x 7 ½
