How to compose and send customized emails to a list of recipients using Perl and Mail::Message.

Yesterday I made an invitation to a concert and sent it to a longish list of friends. To that end I made a table with the needed fields for each correspondent and a program similar to the following. I post them here for my own reference, but they may prove useful to someone else.

#+name: list

#+name: invite
#+begin_src perl -n :results output :var list=list

 1  use v5.36;
 2  use Mail::Message;
 3  use Encode;
 4  my $count=0;
 5  my $time=0;
 6  for($list->@*){
 7      my ($formal, $short, $emails, $intro, $custom, $extra)=@$_;
 8      my $to = "$formal $emails";
 9      my $extra_text=$extra?"You can selectively interpolate additional text\n":"";
10      my $body = decode("UTF8", <<~"END");
11      $Intro $name,
12      This is the main text of the email, in which I can interpolate $custom.
13      $extra_text
14      Regards,
15      Myself
16      Attachment: Some image
17      END
18  
19      my $msg = Mail::Message->build(
20  	From    => 'My Name <my@address>',
21  	To      => $to,
22  	Subject => 'Subject',
23  	data => $body,
24  	file => "$ENV{HOME}/path/to/image.png"
25  	);
26      $msg->send;
27      my $delta_t=1+ rand(1);
28      sleep $delta_t;
29      $time += $delta_t;
30      ++$count;
31      say "$count $time $formal";
32  }

I use the var mechanism of emacs’ org-mode to import the table as a nested array reference into the program. For each line I make a customized email. Notice that in order to attach a file such as an image it is enough to include a line like 24. I asked chatgpt about adding attachments to Mail::Message objects. I got several contradictory and wrong answers, but I finally read the manual. Mail::Message figures out all the mime magick. Furthermore, I used decode from Encode in order to use UTF-8 characters such as accented characters in the body of the message. It seems not to be necessary for the names of the recipients nor the sender. I added some random sleep time after each message (lines 27 and 28), actually, much longer than shown here, in order not to abuse the network and not to appear to be a spammer.