The Maximum Length Limit Of An Email Address is 254, NOT 320!

Ever wondered what is the maximum numbers of characters comprising an email address?
When you design databases, for example, this exact max. number is important to be known (at least for me).
There has been a lot of confusion concerning this number, many people believe it is 320; [{64}@{255}]. This is wrong, as further research all points out to 254!

Maximum Length Limit Of An Email Address

According to the techical report by Dominic Sayers

there is a length limit on email addresses:

That limit is a maximum of 64 characters (octets) in the “local part” (before the “@”) and a maximum of 255 characters (octets) in the domain part (after the “@”) for a total length of 320 characters. However, there is a restriction in RFC 2821 on the length of an address in MAIL and RCPT commands of 254 characters. Since addresses that do not fit in those fields are not normally useful, the upper limit on address lengths should normally be considered to be 254.

What Is Request for Comments (RFC)?

a Request for Comments (RFC) is a memorandum published by the Internet Engineering Task Force (IETF) describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.

~ wikipedia

[RFCs set the standards that define how the Internet works.]

Recommended Reading

• Dominic Sayers Latest RFC Report
• Doug McCaughan – developers heed the ‘robustness principle’
• Email Address Length FAQ