Invite Mod is not sending out email

I set the site to Invitation Only mode, and I tried to send out a few emails to other email addresses but nothing happened. That means that the mailing function for the invite mod is not working.

Does anyone have any idea?

D 7.3.2 latest version

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Than kyou,

cannot quote in Orca, too.

When I try to quote someone, I got this error:

mbstring extension not installed. Warning! Dolphin cannot work without mbstring extension.
Please go to the
Dolphin Troubleshooter
and solve the problem.

now the Quote function is working without any fix, weird shit