Receiving attachments as multipart/mixed or plain text

Marc Wilson wrote:

As should have been obvious, the content of the messages is being determined by the sender, not the receiver.

Hmmm, that can hardly be true, as the exact same emails are being received just fine on my other Lion system?

Marc Wilson wrote:

The content of the message does not change. I'm really sorry that you can't grasp that.

I can grasp it perfectly well, thank you.

Marc Wilson wrote:

So. What email client? How is it configured? Is it the same email client on both machines? Are both machines downloading the same message from the same server?

As I said, everyone is using Macs, both senders are on Snow Leopard. On my end, both Macs are running Lion, and Mail. Both my machines are downloading the same messages from the same server, same Mail config.

I've tried to get to the bottom of this on many fronts, but the fact is it's still 'broken', despite absorbing the above and trying all suggestions. On my older laptop running Lion, I can receive emails with PDF's, XML's, etc without a hitch. On the new laptop running Lion (both are running 10.7.2), those exact same emails (all mail is IMAP and resides on the server) appear in Mail as plain text or multipart/mixed. My ISP has disavowed responsibility, stating that the encoding type is determined by the sender, as have others have. But since one laptop has no such problems with the same emails, it really does appear to be a problem specific to the new laptop.

Any further ideas?

Again, just for clarity - my two laptops are running 10.7.2, using Mail as client. Senders are running Mail on Snow Leopard. Attachments work better if zipped, but even that is no guarantee.

I'm still having this problem, and now the user with whom I had the problem is working on a different machine - he's upgraded to a new MBP and Lion. So we're both on Lion, and I STILL receive many, but not all, of his email attachments as plain text. So frustrating, and so unpredictable. This happens whether he emails from his me.com account or his earthlink account.

Also, Rebuilding the mailbox did not solve the problem - I tried a few times, on a few mailboxes.

etresoft wrote:

How do you know if they are multipart/mixed or plain text?

That part's easy - the emails are just the usual wall of text, the headers are truncated and a lot of info is missing, and the messages say the attachments are multipart/mixed or text/plain.

etresoft wrote:

The only way I've seen that happen is if you have rules that move a message and, for some reason, the rule triggers before the message gets fully downloaded. In this case, rebuilding the mailbox fixes the display.

I think you could be onto something here - this sender is indeed part of a Rule, and the mails are always directed away to a specific mailbox. However, I've yet to see a Rebuild on that mailbox make a difference. I will try again, and again.... :-)

etresoft wrote:

I'm confused about what you are really seeing. Plain text is incompatible with any attachment.

I'm seeing headers like this:

-Apple-Mail=_7064008C-4F08-4ED1-836C-46AC2DC777B2

Content-Transfer-Encoding: quoted-printable

Content-Type: text/plain;

charset=us-ascii

Content-Disposition: attachment;

filename=blahblah.jpg.zip

Content-Type: application/zip;

name="blahblah.jpg.zip"

Content-Transfer-Encoding: base64

UEsDBBQACAAIAA+rMEAAAAAAAAAAAAAAAAAZABAAQVZJUy00LUNhbnRBZmZvcmQtYWRzLmpwZ1VY

DABDBhVPDgYVT/YBFADsvQk8VG/7P37GLlshKkJSyk7Zs5RsIWXfxRgTY2YwMxShVTulkC3Jlj2E

MqEUKiT7nlD2NYYMM/M/M9o+z/P5Ps/z+36/v9e/1/8/t+ucc93Xfd3XvV3nPufc7jeULsqg3A79

U16eAGBmBkgBAMAGcEIAgBHkIHwD4AmyzvO6gicGGs8EHvchLOty8AdM/I3f/J0HtSDbAGYaDwAZ

EKGffD5kz3cdBvCkSD0DYuBRClGi8fzg0XHZi1YOVX8KvEiA9Vr/cbx5FgAkN/64HvRAu8PEjp1E

T1BLAQIVAxQACAAIAA+rMEARrbqTVXQAANXsAAAkAAwAAAAAAAAAAECkgQ9VKABfX01BQ09TWC8u

X0FWSVMtNC1DYW50QWZmb3JkLWFkcy5qcGdVWAgAQwYVTw4GFU9QSwUGAAAAAAMAAwD0AAAAxsko

AAAA

.....

etc

-Apple-Mail=_7064008C-4F08-4ED1-836C-46AC2DC777B2--

So you can see that Mail does indeed see a zip file and that it's encoded base64, but Mail ends up processing it as plain text.

I think you're very much onto something though with the issue of the Rules. I'm going to take this sender out of the Rule for a few days and see what happens.

etresoft wrote:

That really isn't "plain text", that is just all screwed up. Did you copy and paste that directly from the message? It actually has two content types. That is way wrong.

It is crazy, isn't it? Yes, this was actually copied and pasted directly from the one actual message in Mail. As you say, it's completely borked. And, I have other messages that don't have attachments that have their headers utterly screwed up, most of the information missing, etc - e.g. no X-Sender, no path, no IP addresses, no servers, no From, just a To.

I'm becoming convinced that the Rules are the problem here - I think I'm seeing the same problem you're describing - the mail is being re-routed out of the Inbox before it has completely downloaded, and in so doing is 'breaking' the message.

I'm afraid I can't send you the emails concerned, as they're all related to a project I'm NDA-d on. But I'm very grateful for your offer to help. For now, I've removed the sender from my Rule and I'm going to see how that goes - it will probably be weeks before I know if it's a proper cure or not.

etresoft wrote:

There is another possibility. Some e-mail servers perform very heavy virus and phishing scanning on either incoming and/or outgoing messages. They take the messages apart, scan them, and then reassemble them. If you closely inspect the raw output, you may be able to find evidence of that

...[snip]...

Yet another possibility could be the type of e-mail server on either the sender or receiver side.

Yes, this was my first thought actually. This problem suddenly began in the middle of this project when I moved my domain to a new ISP, and so for a long, long time, that was where I was attempting to lay the blame. But I couldn't be 100% convinced, as I also migrated to Lion at the same time. My new ISP insisted that they 'did nothing' to the email, and that the MIME type was entirely the responsibility of the sender. I remain unconvinced by their protests though, and your comment reinforces that thought. They are a pretty geeky host (Dreamhost), but I still have strong suspicions that the domain move, rather than the Lion move, was the real source of the problem. I had never once had this problem with my previous ISP.