Problem downloading attachments in Mail App

Question

Problem downloading attachments in Mail App

We are having problems with the Mail App in several iOS devices (iPhone and iPad).

For some unknown reason, sometimes the Mail App get stuck downloading an attachment.

After some time (several minutes) it downloads the attachment and keeps going.

This happens in several devices and became more noticeable since iOS 18.2. (18.3 and 18.4)

The internet connection is quick and stable (both via Wifi ou LTE 5G).

We have hundreds of others clients using our mail servers (Android / Microsoft) and none of them have this behaviour.

We did also test using Outlook in the iOS devices and with Outlook that problem doesn't happen.

Any idea how to get the Mail App running again with glitches ?

Latest tests setup (Brand new iPad Air):

iPaid Air - 18.3 (22D2062)
On premises mail servers, based on Linux (Dovecot 2.3.4.1)
Accounts configured via IMAPS

Thanks.

FT

Posted on Apr 10, 2025 9:33 AM

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Answer 1

agoodm

Level 1

8 points

Apr 11, 2025 8:41 AM in response to filipe_teixeira

Yup, I am having similar troubles. I run shared email hosting for hundreds of users and some users are coming to me stating that their email performance is bad. In some cases they've spoken to Apple and Apple has blamed the provider (me). Email server in my case is also Dovecot, relevant specs on the server side: Intel Xeon Silver CPU @ <10% load, NVME storage, 128GB RAM. 1Gbps connection less than 1% utilisation on average.

I purchased a new iPhone 13 to test. Added my own account and observed 'hanging' with it saying connecting and once connected sometimes it would apparently 'hang' for some minutes downloading email attachments. Packet captures show that in my case the phone is downloading data from the server approximately 300MB at a time, at speeds >200Mbps. Itll then go silent on the network for some time and refuse to interact with the server. This will prevent it from loading new messages or attachments.

I've tried turning off the 'prevent ip address tracking' and other privacy features. The device has finished the initial setup process.

iPhone and iPad both impacted.

Willing to complete any troubleshooting Apple wants within reason. I've already gone through the normal support channels and ran into a brick wall. Based upon my support history I believe this issue started at the launch of iOS 18 and is still ongoing today.

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Problem downloading attachments in Mail App