Administrators can reduce maximum mailbox sizes per user or globally, see: How to set Exchange Online mailbox sizes and limits in the Microsoft 365 environment for details. The default for Outlook 2003, 2007, and 2010 is 20 GB. The corrupted or damaged PST file can easily be repaired using the smart Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. If the Outlook mailbox size increases to the maximum file size limit, then it may cause some serious problems to the users. This wikiHow teaches you how to increase the size of your Microsoft Outlook mailbox by editing the Windows registry. The default mailbox size for Outlook 2013 or 2016 is 50 GB. Outlook sets limits on the size of these mailboxes, but they can be adjusted by editing your system's registry. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/4\/41\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-1.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-1.jpg","bigUrl":"\/images\/thumb\/4\/41\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-1.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-1.jpg","smallWidth":460,"smallHeight":346,"bigWidth":"728","bigHeight":"547","licensing":"
License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot) License: Fair Use<\/a> (screenshot)
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/0\/03\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-2.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-2.jpg","bigUrl":"\/images\/thumb\/0\/03\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-2.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-2.jpg","smallWidth":460,"smallHeight":342,"bigWidth":"728","bigHeight":"542","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/8\/84\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-3.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-3.jpg","bigUrl":"\/images\/thumb\/8\/84\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-3.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-3.jpg","smallWidth":460,"smallHeight":342,"bigWidth":"728","bigHeight":"541","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/5\/58\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-4.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-4.jpg","bigUrl":"\/images\/thumb\/5\/58\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-4.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-4.jpg","smallWidth":460,"smallHeight":347,"bigWidth":"728","bigHeight":"549","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/3\/3c\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-5.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-5.jpg","bigUrl":"\/images\/thumb\/3\/3c\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-5.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-5.jpg","smallWidth":460,"smallHeight":346,"bigWidth":"728","bigHeight":"547","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/4\/47\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-6.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-6.jpg","bigUrl":"\/images\/thumb\/4\/47\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-6.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-6.jpg","smallWidth":460,"smallHeight":342,"bigWidth":"728","bigHeight":"542","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/7\/79\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-7.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-7.jpg","bigUrl":"\/images\/thumb\/7\/79\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-7.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-7.jpg","smallWidth":460,"smallHeight":344,"bigWidth":"728","bigHeight":"545","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/7\/7e\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-8.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-8.jpg","bigUrl":"\/images\/thumb\/7\/7e\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-8.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-8.jpg","smallWidth":460,"smallHeight":343,"bigWidth":"728","bigHeight":"543","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/9\/96\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-9.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-9.jpg","bigUrl":"\/images\/thumb\/9\/96\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-9.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-9.jpg","smallWidth":460,"smallHeight":344,"bigWidth":"728","bigHeight":"545","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/7\/7a\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-10.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-10.jpg","bigUrl":"\/images\/thumb\/7\/7a\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-10.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-10.jpg","smallWidth":460,"smallHeight":346,"bigWidth":"728","bigHeight":"548","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/6\/61\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-11.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-11.jpg","bigUrl":"\/images\/thumb\/6\/61\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-11.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-11.jpg","smallWidth":460,"smallHeight":346,"bigWidth":"728","bigHeight":"547","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/2\/2b\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-12.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-12.jpg","bigUrl":"\/images\/thumb\/2\/2b\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-12.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-12.jpg","smallWidth":460,"smallHeight":343,"bigWidth":"728","bigHeight":"543","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/2\/21\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-13.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-13.jpg","bigUrl":"\/images\/thumb\/2\/21\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-13.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-13.jpg","smallWidth":460,"smallHeight":346,"bigWidth":"728","bigHeight":"548","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/e\/e2\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-14.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-14.jpg","bigUrl":"\/images\/thumb\/e\/e2\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-14.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-14.jpg","smallWidth":460,"smallHeight":342,"bigWidth":"728","bigHeight":"541","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/a\/a8\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-15.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-15.jpg","bigUrl":"\/images\/thumb\/a\/a8\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-15.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-15.jpg","smallWidth":460,"smallHeight":346,"bigWidth":"728","bigHeight":"547","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/2\/27\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-16.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-16.jpg","bigUrl":"\/images\/thumb\/2\/27\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-16.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-16.jpg","smallWidth":460,"smallHeight":343,"bigWidth":"728","bigHeight":"543","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/0\/0e\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-17.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-17.jpg","bigUrl":"\/images\/thumb\/0\/0e\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-17.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-17.jpg","smallWidth":460,"smallHeight":346,"bigWidth":"728","bigHeight":"548","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/e\/e8\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-18.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-18.jpg","bigUrl":"\/images\/thumb\/e\/e8\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-18.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-18.jpg","smallWidth":460,"smallHeight":346,"bigWidth":"728","bigHeight":"548","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/1\/18\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-19.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-19.jpg","bigUrl":"\/images\/thumb\/1\/18\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-19.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-19.jpg","smallWidth":460,"smallHeight":343,"bigWidth":"728","bigHeight":"543","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/c\/cc\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-20.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-20.jpg","bigUrl":"\/images\/thumb\/c\/cc\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-20.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-20.jpg","smallWidth":460,"smallHeight":348,"bigWidth":"728","bigHeight":"551","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/6\/6e\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-21.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-21.jpg","bigUrl":"\/images\/thumb\/6\/6e\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-21.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-21.jpg","smallWidth":460,"smallHeight":348,"bigWidth":"728","bigHeight":"551","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/d\/d5\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-22.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-22.jpg","bigUrl":"\/images\/thumb\/d\/d5\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-22.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-22.jpg","smallWidth":460,"smallHeight":347,"bigWidth":"728","bigHeight":"549","licensing":"
\n<\/p><\/div>"}{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/3\/30\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-23.jpg\/v4-460px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-23.jpg","bigUrl":"\/images\/thumb\/3\/30\/Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-23.jpg\/aid9778297-v4-728px-Increase-Outlook-Mailbox-Size-on-PC-or-Mac-Step-23.jpg","smallWidth":460,"smallHeight":342,"bigWidth":"728","bigHeight":"542","licensing":"