mails are getting bounced buy 3rd party email massenger work on SMTP

I am in need of a freelancer who can help me resolve an issue with my email campaign. I am currently using Gmail as my SMTP service, but I am experiencing general bouncing with my emails. The primary purpose of my email campaign is informational.

Ideal Skills and Experience:
-Experience with SMTP services and email campaigns
-Ability to troubleshoot and resolve email bouncing issues
-Strong communication skills to keep me updated on progress and any necessary changes to be made.