It's sort of neither -- xf-default just doesn't work exactly like you're hoping. A lot of @xf- stuff is really pre-processor based (as they may include less expressions themselves). The xf-something() functions often are as well.
xf-default() is specifically designed to prevent possible LESS...
You can look at the token_input template to see how we load Select2 (and the CSS).
You can't embed <script> tags in XF if you want them to work with the JS framework. You'd generally use <xf:js /> tags, preferably to load a file. token_input has an example of this, though there are others as well.
VERP changes the return-path on every mail sent and, usually, that address (and often the "from" address) are what need to be verified.
If a system (SES or otherwise) requires a specific return-path header/envelope sender, then VERP won't work.
Saying that, the Amazon docs say they should...
I was hoping to get the content of the email so I could determine if this is a bug in the code or an invalid email, and to confirm exactly how the code is handling this case (it's not supposed to get stuck on invalid emails).
The email may be invalid.
If you look in the bounce email log, do you have any entries that correspond to this time? In particular, ones that may not indicate any action? If so, can you view the email and send us the raw output?
Note that the URL is actually:
There are no unsafe characters there.
Whether or not non-ASCII characters are stripped/romanized is configurable.
You can see all of the latest versions here: https://xenforo.com/community/forums/announcements/
You should make sure you're running the latest versions of all of the relevant software.
If you're already doing that, it potentially sounds like the issues are sporadic. If so and you're not...
Please test the add-on situation, just to confirm. The same code is used for adding a user as editing it, so I don't see why one would fail but the other wouldn't.
If that doesn't resolve it though, I think we'd probably need you to submit a support ticket with ACP and FTP access details so we...
It certainly shouldn't be, though the exact query would be helpful. Can you run a SHOW FULL PROCESSLIST; and either show the query here (or send it to me via a conversation if it has private info)?
It may be helpful to run an EXPLAIN version of that query as well, in case it's doing something...
I believe there's already a suggestion relating to the attachment-media gallery connection. It's not particularly strongly related to this feature, so it's probably best to continue that discussion there (as there certainly are a number of nuances with it).
Just to confirm, what version of XF and XFI (the importers) are you using? XFI 1.0.2 specifically had changes relating to post import performance: https://xenforo.com/community/threads/xenforo-importers-1-0-2-released.153502/