Answer:
1. Pointless email subject
2. Junk and broken links
3. Spelling and grammatical error
4. Spamming the same emails
5. Poor content
Step-by-step explanation:
1. A pointless or misleading email subject. Nobody knows what your email is about, your best bet is to construct a subject that appeals to your targeted audience & increases the chance of the email being opened.
2. Unnecessarily lengthy email filled with broken links. Getting error messages or invalid landing pages is so so uncool (for the sender of the email). Recipients might just blacklist the sender subsequently.
3. Presence of spelling and grammatical mistakes in your emails. Poor spelling & grammatical construct is a turnoff for many a people. Once they spot it, that's a big NO NO!
4. Flooding people with the same email again and again. That's a quick way to get on the nerves of many folks. Nothing hurts more than having a human-sized pest disturbing you inbox.
5. Poor content quality. You got the recipient to open the email and you dish out something useless. Your were better not sending the emails at all.
The list goes on and on but is not restricted to the aforementioned