Emails not always being delivered but in sent folder

[RVicker]

The search advice led to:

5.8 showing as sent, but not always arriving at destination

I’m sure this isn’t about difficulty, as the option to choose between the previous behavior or the currently preferred behavior existed initially but was dropped, presumably to force the issue in his ongoing quest to force MSPs to adhere fully to published standards, which state that email sent his preferred way should be acceptable. This kind of thing is not new. M$ did it with the constant UAC prompts added in Vista to annoy customers into annoying software vendors to adhere to published stan…

No updates since 1/2023.

Which is exactly what is going on. Strange that they let same intra-domain emails through but block inter-domain emails.

Wonder if Thunderbird is going to address this?
And when?