Joan L.

If you create an account while behind a corporate NAT/VPN or DS-lite and someone else also creates an account with the same public IPv4 address they think that you are abusing their system and automatically close "block" both accounts after four days. Hillarious!

If you ask them to unblock the account by using the suggested form you'll get this default answer:

"Dear mail.com Member,

We have forwarded your request to unblock your account to our security department and it was determined that the account in question will remain blocked.

Please note that this is a decision made by our abuse department and we do not have further information we can provide to you.

With kind regards,
Your mail.com Support Team"

Incompetent company, better use a serious provider.