Another tip which maybe someone with more expeience can chime in on is:
For $7 a month you can get office 365. Fantastic email system and if your making bulk instagram accounts i guess you could probably afford $7 a month.
Once you create one email with office 365, you can create alias'. This means you can make:
However, ALL mail to ANY of these addresses goes back to your main email, since you only have 1 mail box and each is only an ALIAS and not a mailbox. Very easy and takes only seconds to create new alias.