Why are messages sent from my iPhone not showing up in my sent folder?
Emails sent from my iPhone do not appear in my sent folder (neither on my phone or on my laptop) however messages sent from my laptop appear in both sent folders without any issues.
Wšykne wótegrona (1)
If all of your mail programs are set up to use IMAP, I would expect to see those folders synchronized correctly in all directions.
What program do you use on your iPhone for sending/receiving mail? Perhaps it has a checkbox in the settings to save sent messages to Sent Items that you need to turn on?
Since it most likely is not Mozilla software on your iPhone, you might find more indepth support from the maker of that mail software.