[CentOS] Does SMTP Connection Drop When Posfix Reload is Issued ?

Dear Community Friends Greetings,

i work with ISP, we host email service for almost 500+ companies and 200+
mail servers relay through my smart host.

i implemented something that when our smart host would become blacklisted.
It will automatic switch to next available smart host (which is ready
sitting). that mean it will start relaying message through another smart
host automatically.

i think i must tell little background as well. it is actually php script
that perform blacklist check every minute through cron. if it found that
IP is blacklisted. It will then insert "relay host =" value in main.cf and
reload postfix service. When IP is no more blacklisted it will then remove
the same directive from main.cf and reload postfix.

everything is working as expected. i have one question, when we reload
postfix does it drop active SMTP session?

for example lets say that remote SMTP server is delivering message to my
postfix that has 8MB attachment. message was not fully transferred. lets
say that 4MB was transferred. and i issued "postfix reload". will that
connection drop or continue to deliver the mail?


Thanks / Regards
Prabhpal S. Mavi