When sending an email with an attachment through the in-app call interface, or directly sending an email with an attachment in an iPhone email, the received email will add its own ATT file. If the email content is in text format, the added attachment will be ATT0000x.txt, and if the email content is in Html format, the added attachment will be att0000x.txt..

Second, the cause of the problem

This problem has nothing to do with the App itself, but is generated by the Exchange mail server. The exchange agreement requires that the attachment must be at the end. If there is text or html content behind the attachment, the content behind these attachments will be put into the generated ATT file to form an attachment and sent to the receiver.

Third, the solution

1, expected solution: program solution, there is no such solution for the time being. The iOS system has an email signature, which will be automatically added to the attachment when we send an email in the APP. Even if the signature is set to blank in the settings, the system will still add two line breaks after the attachment itself, which is invisible in the email sending interface. In order to send multiple attachments at the same time, two line breaks will be added after each attachment, so that each line break represents an att record file. All programs cannot be solved by themselves.

2. Practical solution: change the signature to a meaningless delimiter such as-and drag the attachments one by one before this delimiter (note that the signature is set to blank, but it cannot be dragged to the end. )

Fourth, summary.

Although we haven't found a perfect solution, we can solve the problem by understanding the cause of the problem. To put it bluntly, the email system of iOS is not perfect, and adding attachments to the content itself is wonderful, which is quite good on 163.