From the same sender to the same recipient, printed matter is placed in what's called a mailbag — literally a bag — and mailed.
Literal
Same sender [from-から] same recipient [to-に] addressed mailbag [called-という], literally bag [to-に] printed-matter [object-を] putting-in mail.
差出人 ('sender') and 受取人 ('recipient') are postal/legal terms. 郵袋 (ゆうたい, 'mailbag') is specialized postal vocabulary. 文字通り ('literally') glosses the compound with its plain meaning. 印刷物 ('printed matter') is a postal category. The sentence explains a bulk-mailing procedure with self-aware etymological commentary.