If you're using GMass to send out mass emails (mail-merge) from your Gmail account, you might also want to ensure that your text is crisp, clear, and grammatically correct. My other Gmail extension, Wordzen, edits, proofreads, and even writes your emails for you. It is also a free Chrome extension, and has a team of English experts behind it.
Like GMass, Wordzen adds a button near the Send button when you compose an email in Gmail. Click it and my team of live, human editors will correct and improve your English in about 10 minutes, 24 hours a day.
Compose your email campaign. Then "Wordzen" it to ensure perfect English.Then "GMass" it to send it!
After reviewing your corrected text, click the GMass button to send it.
While many GMass users send emails in non-English languages, Wordzen is currently available only for emails written in English. In time, I'll add support for other languages as well.
Download the Wordzen Chrome extension here.