Why doesn't PDF attachment open in MS Outlook?

Question

IMAP

Colleagues! The crux of the matter is that some files from one recipient (generated and automatically sent from 1C) cannot be opened in MS Outlook using the POP3 protocol. If you do the setting for IMAP, then everything is ok.
For the test on Mozilla Thunderbird, everything is ok, even POP3, even IMAP.
Mail comes in like this: yandex.ru (corporate address) - fetchmail - dovecot.
All the methods associated with antiviruses and cleaning the folder with attachments do not help. I suspect dovecot. Maybe someone faced such a miracle?

Answer 1

Faced a similar problem on POP3. Excel documents are generated for the client from 1C, and he works with mail through Outlook and only through it, units from documents are opened. I tried everything and everything, including changing the format to pdf. The problem was reproduced on Outlook 2010 and 2013, I did not try it on others. After all the tests, it turned out that the files are nullified, and the reason is that the body of the letter did not contain any text, where I did not understand the logic, but after adding the text to the letter, Outlook immediately began to work and the files began to open. To simplify:

Сообщение = Новый ИнтернетПочтовоеСообщение;
Текст = Сообщение.Тексты.Добавить();
Текст.ТипТекста = ТипТекстаПочтовогоСообщения.ПростойТекст;
Текст.Текст = "Текст";

Answer 2

This usually happens because the PDF file is sent without base64 encoding (in 8-bit encoding), which is completely wrong, because. in PDF, line feeds are important, but what can a crooked client that generates PDF do. In your bundle, one of the applications (for example, fetchmail) normalizes line breaks in a letter from CRLF to LF or vice versa. As a result, the PDF is corrupted. Look inside the source text of the letter, if the PDF part is not encoded in base64, then look for the problem in this.

Answer 3

I noticed that Outlook SOMETIMES opens normally. And basically can not open.
Thunderbird always opens.