活动摘要邮件文本中缺少空格字符

[supermathie (Michael Brown)]

@ToddZ

I’m now thinking that despite MailerSend telling me the issues were present in the received requests, it maaaay be happening on their end after all?

I’m finding this likely as well.

For a solid test, I would next take one of the plaintext emails you captured and submit it by hand via your MailerSend account using openssl s_client.