Can I send campaigns from a different 'From' or alias email address or using multiple accounts or shared mailbox?

MailMerge365 now supports sending as an alias or with "SendAs" permissions. Simply change the "From" address.

Note: bounce detection is not available in cases where you're sending as a different mail address and those replies to not arrive your mailbox. Only bounces that arrive in the mailbox that MailMerge365 is running on will be processed.

See here  for more details.