Need advice w/ Email::MIME

SteveTheTechie has asked for the wisdom of the Perl Monks concerning the following question:

I am transitioning from Email::Simple to Email::MIME since I need to manipulate the parts of multi-part emails, and I want to get rid of the hacky code I was using for this with Email::Simple.

I am doing email list expansions in a email list server, and emails to some lists get an unsubscribe link inserted at the bottom of the text (text/plain & text/html) parts.

I have the walk_parts code set up to do the unsubscribe link inserts, and all is good with that.

Where I am running into problems is with resetting the email body parts to the original on each pass to a recipient in the list. I manipulate the headers on each pass but I really do not want to reparse the original email, just reset the body parts. I have to do this so that the unsubscribe links are distinct and I do not append multiple unsubscribe links.

For Email::Simple, I would just do

$orig_body = $email->body;

and then reset the body later with

$email->body_set($orig_body);

However, this does not seem to work with Email::MIME, even though it is derived from Email::Simple. I have tried the following (thinking I needed to reset the parts):

@orig_parts = $email->subparts;

and then to reset

$email->parts_set(\@orig_parts);

However, resetting the parts to the original parts does not seem to always work consistently. Per my test log, I have seen a case where I did the parts reset, then dumped the $email->as_string only to see that the reset did not really occur.

It did occur to me that maybe I need to do something with body_raw, but frankly I am a bit uncertain as to the best approach to reset the email body back to the original without reparsing everything and having to redo all the headers. (major pain)

Anyone have any ideas on how to reset the body parts? (Much thanks in advance.)

Comment on Need advice w/ Email::MIME Select or Download Code

Replies are listed 'Best First'.
Re: Need advice w/ Email::MIME by SteveTheTechie (Novice) on Jun 16, 2015 at 22:31 UTC
Ok, I think I have sorted this out, and I felt I should post a follow-up in case anyone else every stumbles across what I found. I am going to illustrate this with an example... Lets say you want to use Email::MIME in an email list server and you need to walk the text parts of the email to add unsubscribe links that are distinct for each end recipient in the list. You need to somehow save the original state of the parts so that you do not keep adding unsubscribe links on to them... there should be one link that is distinct for each user... You could do the following below to make an independent clone of the parts... this is necessary so that when you walk the MIME parts and add the unsubscribe links, you have an independent cloned structure (@orig_parts below) to revert back to. `@orig_parts = $email->subparts; $email->parts_set(\@orig_parts); # *** like a copy constructor; makes + @orig_parts independent` [download] What I discovered before I added the parts_set above was that @orig_parts was getting updated every time I would subsequently walk the MIME parts and add the unsubscribe link. It was giving me fits. Apparently, there must be sort sort of back reference from the array produced by $email->subparts into the MIME structures for the email. However, when you take the array and feed it back into $email->parts_set, the code rebuilds the email parts... it essentially works like a copy constructor, which makes the original array independent. It does not then get updated when you walk the MIME parts and make parts modifications.	[reply] [d/l]

Replies are listed 'Best First'.

Re: Need advice w/ Email::MIME
by SteveTheTechie (Novice) on Jun 16, 2015 at 22:31 UTC

Ok, I think I have sorted this out, and I felt I should post a follow-up in case anyone else every stumbles across what I found.

I am going to illustrate this with an example...

Lets say you want to use Email::MIME in an email list server and you need to walk the text parts of the email to add unsubscribe links that are distinct for each end recipient in the list. You need to somehow save the original state of the parts so that you do not keep adding unsubscribe links on to them... there should be one link that is distinct for each user...

You could do the following below to make an independent clone of the parts... this is necessary so that when you walk the MIME parts and add the unsubscribe links, you have an independent cloned structure (@orig_parts below) to revert back to.

@orig_parts = $email->subparts;     
$email->parts_set(\@orig_parts);  # *** like a copy constructor; makes
+ @orig_parts independent
[download]

What I discovered before I added the parts_set above was that @orig_parts was getting updated every time I would subsequently walk the MIME parts and add the unsubscribe link. It was giving me fits. Apparently, there must be sort sort of back reference from the array produced by $email->subparts into the MIME structures for the email.

However, when you take the array and feed it back into $email->parts_set, the code rebuilds the email parts... it essentially works like a copy constructor, which makes the original array independent. It does not then get updated when you walk the MIME parts and make parts modifications.

[reply]
[d/l]