I am currently using my Gmail account (say, firstname.lastname@example.org) to manage several other non-Gmail email accounts (for example's sake, email@example.com and firstname.lastname@example.org). I have emails forwarded automatically from both of those other accounts into my Gmail account. For one of those email addresses (email@example.com), I am also able to send mail through Gmail, and my account is configured to automatically respond to all mail sent to firstname.lastname@example.org with an email from the same address.
Due to institutional policies governing b.com's email account (lack of SMTP access), I can forward mail to Gmail but am unable to send mail as email@example.com from my Gmail account. I would therefore like to reply to all mail sent to firstname.lastname@example.org with an email sent from my account email@example.com. Is there any way to do set that up automatically in Gmail?
Sorry so long.