Erlang SMTP client WITH attachments - smtp

Question

I'm looking for one of two things:
An Erlang library that supports sending of emails with attachments
An example of using gen_smtp to send an email with an attachment, since I have already successfully sent emails with this library
It seems there is very little in the way of SMTP client support with attachments out there, although there are plenty of modules that can send plain text emails via SMTP. Anyone have suggestions?
Also, using Windows - I'm not sure the sendmail route is available?
Agus, when I try that exact code, as well as similar code, I keep getting the following error, any ideas?:
** exception error: {badmap,[]}
in function maps:get/3
called as maps:get(content_type_params,[],[])
in call from mimemail:ensure_content_headers/7 (c:/temp/erlang/myapp/_build/default/lib/gen_smtp/src/mimemail.erl, line 667)
in call from mimemail:encode/2 (c:/temp/erlang/myapp/_build/default/lib/gen_smtp/src/mimemail.erl, line 161)
in call from email_test:send_email_with_attachment/0 (c:/temp/erlang/myapp/src/email_test.erl, line 14)
The version of gen_smtp I'm using in rebar.config:
{gen_smtp, ".*", {git, "git://github.com/gen-smtp/gen_smtp.git", {branch, master}}}

Answer 1

Short answer: you can use gen_smtp to send an email with attachment.
If you have used gen_smtp_client:send(Email, Options) or gen_smtp_client:send_blocking(Email, Options), then you can actually generate the Body's Email variable using mimemail:encode/2.
%% #doc Encode a MIME tuple to a binary.
encode({Type, Subtype, Headers, ContentTypeParams, Parts}, Options) ->
...
Below code shows how to send message with email inline body and 2 attachments (test1.txt and erlang.png respectively). The key here is to use multipart/mixed MIME type and construct the email body accordingly.
send_email_with_attachment() ->
From = "noreply#mydomain.com",
ToList = ["target_email#mydomain.com"],
Part2Filename = "/tmp/test1.txt",
{ok, Part2Binary} = file:read_file(Part2Filename),
Part3Filename = "/tmp/erlang.png",
{ok, Part3Binary} = file:read_file(Part3Filename),
Email = mimemail:encode(
{
<<"multipart">>, %%Type,
<<"mixed">>, %%Subtype,
%%Headers,
[
{<<"From">>, <<"No-Reply <noreply#mydomain.com>">>},
{<<"To">>, <<"target_email#mydomain.com">>},
{<<"Subject">>, <<"Mail Subject">>}
],
#{}, %%[], %%ContentTypeParams,
%%(Multi)Parts
[
%%Part 1: this is the inline mail body, note the {<<"disposition">>, <<"inline">>} tag
{
<<"text">>, %%Type,
<<"plain">>, %%Subtype,
%%Headers
[],
%%ContentTypeParams
#{
disposition => <<"inline">>
},
%%Part
<<"Email body (inline) is here blah blah..">>
},
%%Part 2: this is the text file as attachment, note the {<<"disposition">>, <<"attachment">>} tag
{
<<"text">>, %%Type,
<<"plain">>, %%Subtype,
%%Headers
[],
%%ContentTypeParams
#{
disposition => <<"attachment">>,
disposition_params => [{<<"filename">>, <<"test1.txt">>}]
},
%%Part
Part2Binary
},
%%Part 3: this is the PNG file as attachment, note the {<<"disposition">>, <<"attachment">>} tag
{
<<"image">>, %%Type,
<<"png">>, %%Subtype,
%%Headers
[],
%%ContentTypeParams
#{
disposition => <<"attachment">>,
disposition_params => [{<<"filename">>, <<"erlang.png">>}]
},
%%Part
Part3Binary
}
]
},
[] %%Options
),
Opts = [{relay, "smtp.mydomain.com"},
{tls, never}
],
gen_smtp_client:send({From, ToList, Email}, Opts).
This is what you will see in the mailbox: