mailto limits

mailto has no defined limit on the number of characters but there are limits in practice (as of 2015)

Web Browsers:

  •  Apple Safari
    • 705000000
    • Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/601.1.56 (KHTML, like Gecko) Version/9.0 Safari/601.1.56
    • limited by 16GB RAM
  • Mozilla Firefox
    • 268435455
    • Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:41.0) Gecko/20100101 Firefox/41.0
    • limited by maximum string length
  • Google Chrome
    • 2097132
    • Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36
    • limited without explanation
  • Microsoft Internet Explorer
    • 2029
    • Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; .NET4.0C; .NET4.0E; rv:11.0) like Gecko
    • limited without explanation

Email Clients:

  • Mozilla Thunderbird
    • 2097132 works in 1 second
    • 268435455 uses 100% CPU for 2 minutes but fails to render the body and is not usable
    • version 38.3.0
  • SeaMonkey
    • 2097132 works in 5 seconds
    • 268435455 uses 100% CPU for a long time (more than 5 minutes)
    • version 2.38
  • Apple Mail
    • 500000 works in 14 seconds
    • 2097132 uses 100% CPU for a long time (more than 5 minutes)
    • version 8.2
  • Microsoft Outlook
    • trims any url to 2070 in 1 second
    • version 2013