We apologize for the inconvenience caused, as per the description above, Acrobat is crashing/freezing while sending a PDF as an email on your Mac machine, is that correct?
Please check for any pending updates of Acrobat from help>check for updates, reboot the machine after the installation of updates.
Try resetting the preferences of Acrobat, to reset the preferences, refer to How to reset Acrobat Preference settings to default.
Reboot the machine and see if this brings any difference.
If the issue persists, please use Acrobat cleaner tool to remove Acrobat Download Adobe Reader and Acrobat Cleaner Tool - Adobe Labs Reboot the machine and install Acrobat back from Download Pro or Standard versions of Acrobat DC | Non-subscription
If you still face any issue, please create a test user profile with full administrative rights, and try with Acrobat and see if this issue is reproducible.
If the issue still persists, please share the following details:
Let us know how it goes and share your findings.