The effectiveness of email providers for cold emailing can vary depending on various factors, including your specific needs, your target audience, and your sending practices. However, there are several email providers commonly used for cold emailing, and their performance may depend on how well you manage your cold email campaigns and adhere to best practices.

Here are some email providers often used for cold emailing:

Gmail: Gmail is a widely used email service and is suitable for small-scale cold emailing. However, it's essential to follow Gmail's guidelines to avoid being marked as spam or facing account restrictions.

Outlook/Office 365: Microsoft's Outlook and Office 365 are popular among businesses. They offer various features for managing email campaigns.

Apart from the above mentioned, there are some SMTP providers such as Sendgrid, Namecheap, etc that are widely used.