perlemailencodingutf8-decodeprocmail

Decode the utf8 to ISO-8859-1 mail subject to text in .procmailrc file


Set out to write a simple procmail recipie that would forward the mail if it found the text "ABC Store: New Order" in the subject.

 :0
    * ^(To|From).*abc@cdefgh.com
    * ^Subject:.*ABC Store: New Order*
    {

Unfortunately the subject field in the mail message coming from the mail server was in MIME encoded-word syntax.

Subject: =?UTF-8?B?QUJDIFN0b3JlOiBOZXcgT3JkZXI=?=

The above subject is utf-8 ISO-8859-1 charset, So was wondering if there are any mechanisms/scripts/utilities to parse this and convert to string format so that I could apply my procmail filter.


Solution

  • You may use perl one liner to decode Subject: before assigment to procmail variable.

    # Store "may be encoded" Subject: into $SUBJECT after conversion to ISO-8859-1
    :0 h
    * ^Subject:.*=\?
    SUBJECT=| formail -cXSubject: | perl -MEncode=from_to -pe 'from_to $_, "MIME-Header", "iso-8859-1"'
    
    # Store all remaining cases of Subject: into $SUBJECT
    :0 hE
    SUBJECT=| formail -cXSubject:
    
    # trigger recipe based also on $SUBJECT content
    :0
    * ^(To|From).*abc@cdefgh.com
    * SUBJECT ?? ^Subject:.*ABC Store: New Order
    {
    ....
    }
    

    Comment (2020-03-07): It may be better to convert to UTF-8 charset instead of ISO-8859-*.