If you are trying to tell someone on an email about the fact that you are sending them too many emails, do you say Lots of Email or Lot of Emails
I have seen both, and used both, so I would say neither is obviously incorrect. If you read Wiktionary, they note that “certain style guides recommend against the countable use of email” but also that people do it all the time.
I would also just note two other things: Email is an accepted spelling, however so are e-mail, eMail, and email. Second, the root word mail is not flexible in this way: you must say lots of mail. “Lots of mails” is not incorrect, but very archaic and incorrect sounding.
Why not "too many emails"? That sounds better than either "lots of emails" or "a lot of email".
By the way, I think you would want to say a lot, not lot. "A lot" means many.
Another way to say it would be "Sorry I've been sending you so much email".
I would consider emails to be a shortened form of "email messages," so yet another safe way to say it would be "Sorry I've been sending you a lot of email messages."