Okay, my misunderstanding.
I would have no idea what the problem might be, however, I think you should specify whether this problem occurs only with those two recipient servers (gmail and hostgator) and not with other contacts.
And also if you were using old versions before and didn’t have this problem
I’ve checked again and interestingly, there is a deltachat folder in the webmail, as well as all messages being sent from deltachat are beimg shown in the sent folder. Also, I can receive the emails in deltachat, but even when I reply to them, the same issue occurs. It’s there in the sent folder, but doesn’t reach the destination
are you sure the emails arrive at all? ex. try using another email client instead of DC with that email account and see if the emails then arrive to the other side
alternatively, verify the sent message doesn’t have a red exclamation mark, and long press the message and click the (i) info button to see more details
in worse case it is that the receiving(or sending) provider is detecting something in the emails (ex. encryption?) and filtering them out in which case it is not the fault of Delta Chat