If you delete messages from the outbox, does it stop it from being sent?

Hi,

I typed up an e-mail earlier and tapped send on my Mac Mail (Gmail-hosted account), and put my laptop to sleep. I opened it up 4 hours later and it was under outbox, and it said the time session timed out.

I deleted it from the outbox, and drafts as well, just in case so that I could send it again since this one said morning, and it is actually already afternoon.

The e-mail is very important (committee dissertation invite) so I don't want to look like a dummy sending it twice, one saying morning and the other afternoon

Is it safe to say I can send it again without worrying that it might send the other one later on as well?

Thank you!