Automatically created templates look attractive, but I don't think anyone will read them; it will merely look like an advertisement.
Thus, I prefer plain text personalized emails over them, but not against adding visuals. You can surely add images or videos if they fit naturally.
Also, an attractive subject line is a must if you want to get your emails opened.
Start with a greeting sentence, and then keep your message to the point—no need to add unwanted stuff.
Track the performance of email campaigns.
If you are sending bulk emails, it would be nice if you verified the email list first. It is important to avoid sending emails to the wrong addresses. Just search on google about "Top 10 bulk email verification and validation services" You will find exactly what you are looking for in the first blog.
The most effective email marketing strategies are:
Send a personalized email
Always send a personalized email, so the user feels personal touch rather than a sales email.
Keep your subject line short
Keep your subject line short and attractive. Make sure you don't use any sales subject or bluff statistic, which reduces your open rate.
Segment your subscriber
When you are planning for your email marketing, make sure you have a clear idea about your targeted audience according to age, region, gender, company, industry, a past purchase, etc.
Schedule your email according to the time zone
Maybe your targeted audience is from a different region. Schedule your email according to the perfect time so your email gets land and must be open to your targeted audience.
Send mobile-friendly email
Most people are accessing their emails through mobile, so if you are planning to send an image or infographic, make sure that it will be mobile-friendly and conveyed the way you want.