已解决！我希望这对将来的其他人有所帮助..即使我启用了 gmail访问不太安全的应用程序"，它仍然拒绝 PHPmailer 登录..似乎由于某种原因 gmail 不接受端口 587，至少对我来说，所以我把它切换到 465 并且一切都开始正常工作了.

Resolved! I hope this helps others in the future.. Even though I enabled gmail "access to less secure apps" it kept rejecting the PHPmailer sign in.. Seems that for some reason gmail wasn't accepting port 587, at least for me, so I switched it to 465 and everything started working right a way.

作为这个答案的一个优点，至于@Amit Merchant 在评论部分提出的建议，我不知道 ***.com/a/33667250/1485183 中的最后一条评论说什么，它基本上显示了一个 gmail 功能在为我的问题寻找解决方案时，我从未发现或听说过:accounts.google.com/DisplayUnlockCaptcha

As a plus for this answer, as for what @Amit Merchant suggested in the comment section, I wasn't aware of what the last comment in ***.com/a/33667250/1485183 says, it basically shows a gmail feature I never found or heard when looking for a solution for my problem, that this: accounts.google.com/DisplayUnlockCaptcha

我敢肯定，无论是用于 phpmailer 还是任何其他库，这都会在某一天帮助到某人.

I'm sure this will help someone some day whether if it's for phpmailer or any other library.