[Tutor] sending email via SMTP: code review requested

[Brian van den Broek]

On 5 May 2014 13:53, Steven D'Aprano <steve at pearwood.info> wrote:
> On Sun, May 04, 2014 at 07:00:24PM -0400, Brian van den Broek wrote:
>> Hi all,
>>
>> I am playing with the smtp and email modules from the standard library
>> of Python 2.7.3 (I also want it to run on 2.6.6). I've not found the
>> going easy; the SMTP and RFC 2822 standards are not ones I have worked
>> with before.
>
> Neither have I :-(


Hi All,

Thanks for the feedback, Steven. (And to Japhy for the earlier reply).

>> I have something that works, but I am not confident I am
>> doing the right thing. For that matter, I am not very confident that I
>> am not doing the wrong thing.
>
> The code seems nicely written, it's understandable and easy to read. I
> haven't tried running it yet, but nothing stands out as obviously wrong.

Well, gosh'n'golly-gee.

>> I would very much appreciate some more experienced eyes on the code below.
>> In addition to any outright errors concerning interaction with an SMTP
>> server and constructing a MIME message, I would of course also welcome
>> style comments. (Preemptively, I will note it isn't obvious I ought to
>> have gone OOP with this.)
>
> Having the SMTPSender object send a message automatically on
> instantiation strikes me as a bit wiffy. I'm not sure if it's a good
> design or not. But for a simple cron job, it may be fine.

That is a pattern I often have and for which I often have an
associated spidey-tingle. If I have a class that exists to handle some
processing and then be heard from no more, it always seems a bit funny
to do:

my_thing = MyOneTimeTaskClass(vars)
my_thing.do_it()

as every time I instantiate MyOneTimeTaskClass I am going to
immediately ask the instance to do the things it does.

Either way feels, as you say `wiffy.' (I think I shall steal that.)


> [...]
>> And, as I side note, could anyone explain why changing a first world
>> of a body line 'From' to '>From' is the preferred standard?
>
> Because it's a dirty, nasty hack invented by somebody who wasn't
> thinking very carefully at the time, and now everybody does it. Bleh.
>
>> I
>> understand what the problem is that is being solved, but as most email
>> clients interpret a leading '>' as an indication of quoting, I would
>> have thought ' From' or something like '-From' would have been better.
>> If I have my own code deal with the problem in one of these ways, will
>> I be breaking anything?
>
> Yes. The idea is that your email client should recognise the hack when
> it sees a line ">From ..." and hide the leading ">". So if you use some
> other character, say, "!From ...", other people's mail clients won't
> know to hide the "!".


Oh dear.

I developed my code mostly checking the resulting email with the gmail
app on Android. It doesn't handle things this way; instead, some
(variable! No, really) portion of the message body gets displayed as a
quote. I would declare my surprise, but little about the act of malice
that is the gmail Android app could surprise me now. (Unlike the web
interface, there is quite literally no way to send plain text from the
app.)

Anyway, thanks again,

Brian vdB