Hello Juan Lai and good afternoon. Sorry for the delay in responding to you here.

I encountered a ticket today with a similar result in that the attachment does not display on iOS via EAS, but displays properly in webmail and connected email clients. Looking at the raw content, this looks to be related to the Content-Type: Multipart/Mixed/Alternative change as well, and is being introduced by a chance in the user's PBX vendor software. Can I have you submit a support ticket on this if you see the problem under our latest release please? 

Hello Kyle,

   I had my staff submitted one ticket with similar issue, and the case number is [335-28EECB50-0B6B] . 

I am not sure if this issue is related. 

  But I have to say this  Content-Type: Multipart/Mixed/Alternative issue, sometimes became winmail.dat on
mobile devices especially iOS existed since my company implemented SmarterMail (V14). It's happened

from time to time.

   anyway, I will have my staff to create a ticket as well, though we thought the new MIMEkit will fix it.

   Thanks

rds

Juan Lai

Hi Juan,

we are having issues probably with multipart/related but only on Iphone/iOS-devices that the attachment is not displaying. If I manually change/edit a received .eml for testing purpose multipart/related to multipart/mixed the email with attachment is being dispayed and I can even access the attachment that was not showing up first.

As I understood your post correcty you have issues with mails created/sent by iPhone/with iPhone Mail - we are the SmarterMail customer with PBX-created emails - on which system do you have issues? Outlook or only at other iPhone/iOS-devices?

What I find @Google is that there probably should be better met some requirements concerning format and composing/creating emails. At least for multipart/ being displayed correctly @iOS-devices. But until now there is no solution or guidance what is wrong/what needs to be changed or fixed.

Regards,
Thomas

Hello Thomas,

    We mostly have the multipart/alternative & multipart/mixed to "read" with mobile devices with mail app, no matter android or iOS. But if you are talking about mail created, this only happened on iOS so far. 

   Thanks

rds

Juan Lai

Hello Kyle,

    Zach wants to close the [222-29121496-0B08]  ticket. He said "There have been improvements to both IMAP and EAS" from the latest build. 

    Well, we are still waiting for the new MIMEKit to release then upgrade. Just let you know the status so far.

rds

Juan Lai

Hi Juan,

concerning our issues with the VoIP-phone-system/mailbox-messages with attachments (.wav, .mp3, .pdf) the vendor fixed this by using multipart/mixed - this can be displayed correctly even @iPhone. Their "multipart/related"has/had issues.... There was a problem with the multipart/mime where the iPhones behaved differently than the other devices. Probably this is an issue inside iOS, but I do not expect that Apple will change/adjust their operating systems.

Concerning your "on iPhone/iOS created/sent emails" - I do not have any idea... if this affects only mails created/composed @iOS-devices then you should report this to Apple or post this at AppleCommunities and hope for some comments/ideas there.


In case you need information about our issues with the emails/attachments you could check this out:
I found the following as an explanation what happens with iOS native MailClient/App - what is going wrong;
https://github.com/bcit-ci/CodeIgniter/issues/4583
*****
When composing a mail with a multipart/alternative body the attachments are lumped into the same multipart/alternative part as the message body alternatives. iOS devices will display only one of the parts, typically the last attachment (i.e., only one attachment and no body displays).

The solution is that the multipart/alternative part should only contain the text_part and html_part, and that part should be added to an enclosing multipart/mixed that also holds the attachments.
*****

Regards,
Thomas