Supported Providers and Limits – mxHero Help Center

This page collects the supported providers and the fixed limits of Mail2Cloud in one place: size and length limits, time windows, retention periods, session lengths and notification frequencies. Each row links to the page that explains the feature.

Supported platforms

Mail systems

Platform	Email Flow rules (gateway)	Mailbox rules (User Mailboxes)	Directory sync
Microsoft 365	Yes	Yes (Microsoft Graph)	Yes
Google Workspace	Yes	Yes (Gmail API)	Yes
IMAP server	–	Yes (no mark-as-processed)	–
LDAP directory	–	–	Yes
Any SMTP mail system or border gateway	Yes	–	–

See Routing Architectures and Accounts and Directory.

Cloud storage providers

Provider	Organization connection	Individual accounts	Metadata	`#` kept in names	Large-file upload
Box	Yes (Box Enterprise or Business)	Yes	Yes (metadata templates)	Yes	Single request
OneDrive and SharePoint	Yes (admin consent)	Yes	No	No	Upload session for files of 4,096,000 bytes or more
Google Drive (incl. shared drives)	Yes (Google Workspace Marketplace app)	Yes	No	No	Handled by Google's client
Egnyte	No	Yes	Yes	No	Single request
Egnyte Gov	No	Yes	Yes	No	Single request
Dropbox	Teams/Business only	–	No	No	Single request
mxHERO Shares	Yes (built in)	–	Yes	Yes	100 MB per manual upload in the End User App

For "single request" providers, the provider's own single-upload size limit applies. See Storage Overview and Link Security Options by Provider.

Mail processing

Item	Limit	More
Maximum message size accepted by mxHERO	256 MiB (your mail system's limit is usually lower)	Network Endpoints
Recipients per message	1,000
Hop limit before a message is treated as a loop	50 `Received` headers (then `554` rejection)	Mail Loops and Bounces
Delivery retries to the next server	Up to 24 hours
SMTP ports	25 and 587 on `smtp-in.mxhero.com` and `smtp-relay.mxhero.com` (no port 465)	Network Endpoints
Enabled Email Flow rules per organization	1,000	How Rules Work
Time for rule and account changes to apply	About 1–2 minutes
Transport Agent value	32 hexadecimal characters, one per organization (plus a previous value during rotation)	Gateway Settings
Gateway Secret transition period	0–60 minutes	Gateway Settings
SMTP-Auth users	2 per organization	Gateway Settings

Rule actions

Item	Limit	More
Temporary Hold duration	2–60 minutes, 1–24 hours or 1–10 days; default 20 minutes	Temporary Hold
Extended (paused) Temporary Hold	Expires 7 days after it was extended, then the message is rejected	Managing Held Emails
Request Approval expiration	1–30 days or 1–24 hours; default 7 days; the message is rejected at expiry	Request Approval
Request Approval reviewers	Up to 10 per rule	Request Approval
Minimum reminder interval (hold and approval)	2 h for expirations under 24 h; 6 h up to 72 h; 12 h up to 168 h; 48 h above that. Never longer than the expiration.
Storage retries for Protect Attachments, Secure Email, Zip Attachments	Up to 45 minutes, then the original is delivered (or bounced if set to reject)	Storage Upload Failures
Storage retries for archiving and copy rules	Up to about 3 hours, then kept for Rules › Reprocess Emails	Reprocess Emails
Storage retries for Drag and Drop	Up to 5 days	Drag and Drop
Generated link passwords	0–20 each of numbers, symbols, lowercase and uppercase letters (default 2, 2, 4, 2)	Zip Attachments

Notification text limits

These limits apply to rule notifications (hold, approval, block, zip, password) and to storage notification templates.

Field	Maximum characters
Button (call-to-action) label	54
Title	115
Subject tag	100
Email subject	150
Message line	500
Body text	1,500
HTML header or footer layout	7,500
Template name	100

See Notification Templates.

File and folder names

Item	Limit	More
Folder or file name	200 characters per name, cut before the extension and any `_vN` suffix are added	File and Folder Naming Rules
Total path length	No mxHERO limit. The provider's own limit applies (for example OneDrive and SharePoint).
Removed characters	Emoji and other symbols, control characters, `: \ / * ? \| < > % ' "`; `#` except on Box and mxHERO Shares; trailing `.` and `~`	File and Folder Naming Rules
Empty name after cleaning	Replaced by `EMPTY`
Files per Box folder before versioned names switch to timestamps	800 (when overwrite is off)

Storage accounts

Item	Limit	More
Simultaneous uploads per storage account	Box individual 8, Box organization 10, OneDrive 8, Google Drive 8, Dropbox 8, Egnyte and Egnyte Gov 4, mxHERO Shares 12	Storage Load Balancing
Accounts in a balanced pool	100	Storage Load Balancing
Re-authorization email to the account owner	At most once a day, for the first 7 days after the failure	Re-authorizing Storage Accounts
Re-authorization link	Valid 7 days

Auto Filing

Item	Limit	More
Name and description of policies and template definitions	100 and 500 characters	Copy Policies
Test email upload (Variables › Test variable)	`.eml` or `.msg`, 25 MB	Custom Variables
Dataset CSV import	`.csv` under 2 MB, one `key,value` per line	Datasets
Dataset synchronization from storage	Every 6, 12 or 24 hours; folders up to 100,000 items	Datasets
Link expiration in a security definition for mxHERO Shares	Up to 365 days	Security Definitions and Policies
OCR per attachment	Up to 20 pages or images per pass, 60 seconds; results cached 14 days	OCR Text Extraction

Accounts and directory

Item	Limit	More
Account CSV import	8 columns; up to 20 files of 100 MB each; sent in batches of 1,000 accounts	Managing Accounts
Scheduled directory sync	Once a day at a chosen hour and time zone; without a schedule, 24 hours after the previous run	Groups
Continuous mailbox rules	Re-run about every 5 minutes, plus push notifications for Microsoft 365 and Google	Copy Emails
Mailbox account connection errors	After 20 in a row, retried every 8 hours	Mail Not Processed

Item	Limit	More
Admin Dashboard session	Ends 3 hours after the last activity	Registering and Signing In
Re-authentication for sensitive changes	Required if the last sign-in was more than 1 hour ago	Users and Roles
Two-factor code (email)	6 digits, valid 10 minutes, 10 attempts	Security Settings
Trusted device (skip 2FA)	7 days	Security Settings
Dashboard password	At least 12 characters, with uppercase, lowercase and a non-alphanumeric character	Registering and Signing In
Registration link	Valid 1 hour, single use
Password reset link	Valid 20 minutes, single use
SAML one-time sign-in code	60 seconds	Single Sign-On with SAML
End User App session	1–48 hours, or No expiration (10,000 hours, about 14 months)	Security Settings
mxHERO Shares recipient sign-in code	6 digits, valid 10 minutes, single use	Recipient Experience

mxHERO Shares

Item	Limit	More
Subdomain	Letters, digits and `-`; up to 40 characters; cannot be changed after setup	Shares Settings
Storage region	US or JP; chosen once at setup (support can move it)	mxHERO Shares Overview
Retention	One year (default) or permanent	Shares Settings
Link expiry when none is set	365 days with one-year retention; none with permanent retention	Link Types and Security
Settings changes take effect	5–10 minutes
Manual upload in the End User App	100 MB per file	Managing Shared Files
Malware file download link (admin)	Valid 5 minutes	Malware Detection

Reports, notifications and retention

Item	Limit	More
Email Flow Logs search window	The last 12 months (rolling); default search is the last 7 days	Email Flow Logs
Email Flow Logs delivery-status filters and CSV "final status"	Messages from 2026-05-26 onward	Email Flow Logs
Email Flow Logs results per request	100 (use Get more for the next 100)
Email Flow Logs CSV report	Up to 500,000 rows; kept 5 days	Email Flow Logs
User Activity events	Kept 1 year	User Activity
Notifications	Kept 30 days	Notifications Report
Notification digest emails	Hourly, daily or weekly per type and level (UTC)	Notification Settings
Monthly usage email	1st of each month, 00:00 UTC, for the previous month	Notification Settings
Usage Reports range	30, 60 or 90 days	Usage Reports
Link tracking data	Kept 30 days per message; repeat opens from the same IP and browser within 30 minutes are not counted	Link Tracking
Tracking notifications	At most one per message, recipient and type in 21 days; muting lasts 29 days	Link Tracking

AI features

Item	Limit	More
AI Question answer cache	1 hour per identical request	AI Question Conditions
AI Question provider timeout	30 seconds (temporary errors are retried)	AI Question Conditions
Store in AI retries	Up to 5 days	Store in AI
Message body indexed by Store in AI	Roughly the first 4,000 words	Store in AI
AI index retention period	At least 30 days, set by mxHERO on request	Store in AI
Scopes a user can search through mxMCP	1	Store in AI
mxMCP sign-in code	8 characters, valid 15 minutes	Installing mxMCP
mxMCP connected assistant session	Refreshes automatically; ends after 30 days without use	Installing mxMCP
mxMCP demo account sessions	24 hours, no refresh	Demo Account
mxMCP answer size	About five full messages per answer	Installing mxMCP
mxMCP exact identifiers per search	3	Installing mxMCP