I discovered an interesting problem with 9.3.2 PHP/SMTP. I'm using 4-5 cron jobs (sending e-mails to customers). If a word (a name) starts with a special character (ÍŰÁÉÚŐÓÜÖ), the first letter is always missing in the e-mail body and in the target's name.
I downgraded to 9.3.1 and everything is working well again. The problem occures only if I'm using a cron job.
Unfortunately, there's not enough information here to understand the cause of the problem.
A simple code snippet that shows what you are doing might help..
The problem was with the cron job. This solved the problem, if somebody has the same, try it: Locale settings for your cron job
Now it works with 9.4.0 fine!