Quotas and limits¶
Mailbox space (quota)¶
Each mailbox has a maximum size, set by the plan (for example 5 GB, 50 GB, 100 GB or 200 GB). The percentage used appears at the bottom of the folder list, under Preferences > Folders.
All folders count towards the quota, including Sent, Deleted Items and Spam. Emptying Deleted Items and removing old messages with large attachments is the quickest way to free up space.
When the mailbox is close to the limit, the domain administrator can receive warnings at 90 % and 95 %. Once the quota is exceeded, new messages are rejected. See Mailbox full / quota exceeded.
If you need more space, ask your company's service administrator to change the mailbox plan.
Sending limits¶
| Limit | Value |
|---|---|
| Maximum size per attachment in webmail | 75 MB (shown in the new message window) |
| Maximum file size when importing contacts | 200 MB |
Each mailbox's sending volume is set by the administrator (normal or large). For campaigns and bulk sending, talk to support: personal email is not the right channel for that.
Large messages
Even within these limits, the recipient's server may reject large messages; many only accept 10 to 25 MB. For large files, send a sharing link.
Why a message is bigger than its attachments¶
Mail server size limits apply to the encoded message, as it travels over the internet, not to the sum of the attached files.
To travel by email, each attachment is converted into text (base64 encoding, inside the MIME format). This conversion increases the size by about 35%. On top of that, every server the message passes through adds information to the header (where it passed, the result of the anti-spam and antivirus checks).
| What you attach | Approximate size of the message sent |
|---|---|
| 2 files of 1 MB | about 2.7 MB |
| 10 MB of attachments | about 13.5 MB |
| 20 MB of attachments | about 27 MB, above many recipients' limit |
As a rule of thumb, expect messages to be at least a third larger than the files you attach. If the recipient accepts 25 MB, keep attachments under about 18 MB.
Servers limit the encoded size because that is the size they receive and store: to measure the "original" size, they would first have to accept and decode every large message.